View Full Version : Let's design a new service rifle and cartridge...
BrigandTwoFour
06-24-13, 23:00
A lot of discussion these days is focused on the current "big 3" alternate calibers of the AR-15 platform: 6.8 SPC II, 6.5 Grendel, and 300 BLK. Each one offers various gains (or losses) when compared to the standard 5.56 NATO round used in our beloved rifles. At the same time, in other areas, the gun world is abuzz with talk about how the Army effectively shut down the individual carbine competition.
This got me thinking. Why not start a discussion about what exactly a new rifle should look like? I don't want to limit it just to the rifle, though, so let's discuss the cartridge as well. All of the stuff that we've been talking about as far as cartridge variations and rifle design has been limited by two factors:
- All of the new carbine/rifle designs are based around continued use
of 5.56 and STANAG magazines
- All alternate cartridges we talk about have been a compromise of capability and the ability to fit into the AR-15 platform
So let's discard those requirements for this discussion. If you read the original ORO reports about the .223 and the AR-15, it becomes apparent that the story of the Ar-15 is every bit as much about the evolution of the .223. This discussion should be no different.
So here are the ground rules:
1. We must determine an ideal cartridge for general infantry issue. You cannot use theoretical technology that doesn't exist yet or will be difficult to obtain in quantity. Bullets must conform to current laws of armed conflict.
2. We must "design" a rifle to use said cartridge and be the standard issue long arm to US forces
3. Costs should be kept reasonable, but not stingy. This is all an academic exercise and does not need to fit into any actual fiscal policy. But the end result should still be practical.
Some considerations based on past experiences:
The original ORO research that led to the M-16 determined that an average military firefight (up through WWII) occurred within 100 yards. Beyond that range, hit probability decreased dramatically. Beyond 300 yards, the chance of being struck by a bullet was essentially random. Beyond 300 yards, you were about as likely to be killed by a grenade or artillery as you were a rifle round. The .223 was developed to meet this spec, though the maximum range spec was extended to satisfy the Marine Corps. While the historical engagement distance is relatively close, experiences in Afghanistan have demonstrated a need to have consistent capability at longer ranges.
During testing of the .223 and the M-16, penetration and intermediate barrier was found to be a significant issue when compared to the 7.62x51. Not much has changed in that regard; and the desire for a better performing round like the 6.8 SPC and 6.5 Grendel illustrate the fact. Whatever cartridge we come up with should demonstrate range, accuracy, penetration, and good terminal ballistics.
Accuracy through repeated fire was important during the original ORO tests. Whatever configuration we choose should continue in this tradition, but realize that the ammunition/weapon combination contracted today is 2 MOA to 6 MOA, not exactly precision work. Sacrificing precision in order to gain something else is acceptable, though the choice is up to you.
Useful References
Hitchman, N. (1952). Operational Requirements for an Infantry Hand Weapon.
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=AD0000346
Ehrhart, T. (2009). Increasing Small Arms Lethality in Afghanistan:
Taking Back the Infantry Half-Kilometer.
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA512331&Location=U2&doc=GetTRDoc.pdf
BrigandTwoFour
06-24-13, 23:13
To kick things off, here are my thoughts.
First, despite being active duty USAF, I honestly don't have any experience with using small arms in combat. My career field is nuclear weapons, not any direct action roles. And in seven years, the Air Force just hasn't seen fit to even let me qualify with anything other than the M9. But I am an unabashed technical nerd who reads and absorbs everything I can about small arms. I have played with a wide variety of arms, and have many friends who routinely go into harm's way in varying capacities including pilots, NSW, PJs, and other combat roles. We talk pretty often. That said, in my opinion, a new generation of infantry combat weapon would have a few basic characteristics:
1. As light as practical. With the trend towards heavier and heavier combat loads, the need for a lighter weapon grows more important. Research dating back to early last century also points out that being able to carry more ammunition dramatically increases the capability of the individual. We also have to consider the widespread entry of women into combat roles.
2. Modularity. I dislike quick swap barrels, as I think it introduces too many variables, but I do like the way an upper receiver can be swapped on the M4 or SCAR depending on the needed role. The ability for an individual to quickly tailor the weapon to their need is a force multiplier.
3. While I am a big fan of DI rifles, I think going to a piston system makes more sense for a hard use rifle. Improvements in the piston platform and manufacturing capability have mitigated the previously held concerns of accuracy and reciprocating mass on pistol rifles. I believe LMT and HK have demonstrated this with their piston platforms. That said, there is still a weight concern.
4. Any future combat rifle should be fully ambidextrous. Magazine release, bolt catch, and safety controls should all be readily available to the firing hand while maintaining a proper grip. I like a forward mounted non-reciprocating charging handle (a la the ACR).
5. I think an effective point target range of 500-700 meters is ideal for a general-purpose carbine/rifle. While the historical research showed the practical maximum range for most conflicts was 300 yards, recent experiences show that a longer capability is still needed.
As far as cartridges go, I really like the work that was done on the 6.8 SPC II. I think the .277 bullet provides a lot of opportunity, especially when more velocity can be gained. A 135 gr SMK launched at 2800 fps is still supersonic at 1000 yards, and still retains 800 ft-lbs of energy at 700 yards (enough to take down a deer). Additionally, the work done on the 6.8 SPC shows that shorter barrels can still provide plenty of velocity.
I think using the .277 bullet in a slightly larger case would provide the best balance of power, range, and capacity.
My first thoughts jumped to a slightly shorter iteration of the .276 Pedersen round - basically give that the treatment to where it runs like a slightly longer 6.8SPC in terms of chamber pressure and neck dimensions. Breaking from STANAG limitations, even if only a bit, may not happen, but it should for the purposes of this discussion.
I do like the polymer lower Aluminum upper setup used by the SCAR and Masada/ACR, and I'd agree that borrowing an existing piston system creates the greatest opportunity to field something useful. With those should be a simple ambidextrous pull down/push up bold release, otherwise both of those are good working examples.
Since multiple services are going to want a PDW variant, that needs to be considered in the design - but something like that with a 8"-12.5" barrel and collapsing/folding stock will fill the role adequately.
The biggest concern I have is that weight will be a compromise - for general infantry use, this will still come in at close to ten pounds when equipped with a Squad Common Optic, White/IR Light and Laser, Magazine, and Sling. This would be a great fighting gun out to 600m, for sure, but not be that handy in really urban fighting. Using a more PDW oriented version with a reflex optic could fix a lot of that, but this is back to the case where the entire family of weapons would need to be adopted before any logistics start to improve at all.
What about the 7 x 46mm uiac?
I know far too little to even attempt to put it into the ultimate service rifle.
BrigandTwoFour
06-24-13, 23:49
Llama,
After you mentioned the PDW, I realized I had forgotten about the CZ Bren 805, which is another weapon that I think does a lot of stuff right. But, like the SCAR, the upper receiver just appears too "tall." I wonder if its even possible to keep a lower profile receiver while still using that style piston?
Agnostic,
I had never heard of that cartridge, and it looks really interesting. I didn't realize DocGKR had mentioned it in a thread here at M4C (https://www.m4carbine.net/showthread.php?t=19936). I wonder what the recoil comparison would be between the 7x46 and some higher powered varient of 6.8?
I come back to the training requirement. I feel like a lot of the reason we got away from the 7.62x51 as standard issue due to issues of weight and controllability in a standard rifleman platform under fully automatic fire. From a cost standpoint, it would take a lot more ammunition to properly train a single shooter with a heavier recoiling round.
The 7x46 does offer an interesting logistical aspect, though. If it can effectively replace both the 5.56 and the 7.62 for standard platforms, that helps the logistical supply chain quite a bit. Good find.
Llama,
After you mentioned the PDW, I realized I had forgotten about the CZ Bren 805, which is another weapon that I think does a lot of stuff right. But, like the SCAR, the upper receiver just appears too "tall." I wonder if its even possible to keep a lower profile receiver while still using that style piston?
Agnostic,
I had never heard of that cartridge, and it looks really interesting. I didn't realize DocGKR had mentioned it in a thread here at M4C (https://www.m4carbine.net/showthread.php?t=19936). I wonder what the recoil comparison would be between the 7x46 and some higher powered varient of 6.8?
I come back to the training requirement. I feel like a lot of the reason we got away from the 7.62x51 as standard issue due to issues of weight and controllability in a standard rifleman platform under fully automatic fire. From a cost standpoint, it would take a lot more ammunition to properly train a single shooter with a heavier recoiling round.
The 7x46 does offer an interesting logistical aspect, though. If it can effectively replace both the 5.56 and the 7.62 for standard platforms, that helps the logistical supply chain quite a bit. Good find.
That would be my question about it, weight and recoil.
A 6.5-7mm barrier blind projectile fired from a cartridge case with about 40 gr of capacity loaded with flash suppressed, heat stable powder optimized for full burn in a 16" barrel would be about perfect. Case head should be smaller diameter than current 7.62x51mm and case length should be a bit shorter--perhaps something around .440-460 base with a 46-47mm length; maybe using polymer case technology. Even better, something like a cased telescoping 7 mm could be used.
A 6.5-7mm barrier blind projectile fired from a cartridge case with about 40 gr of capacity loaded with flash suppressed, heat stable powder optimized for full burn in a 16" barrel would be about perfect. Case head should be smaller diameter than current 7.62x51mm and case length should be a bit shorter--perhaps something around .440-460 base with a 46-47mm length; maybe using polymer case technology. Even better, something like a cased telescoping 7 mm could be used.
Or caseless?
A 6.5-7mm barrier blind projectile fired from a cartridge case with about 40 gr of capacity loaded with flash suppressed, heat stable powder optimized for full burn in a 16" barrel would be about perfect. Case head should be smaller diameter than current 7.62x51mm and case length should be a bit shorter--perhaps something around .440-460 base with a 46-47mm length; maybe using polymer case technology. Even better, something like a cased telescoping 7 mm could be used.
Take a 300 Savage and neck it down to 6.5? I wish I had my PO Ackley books here. Bet it's been done
BoringGuy45
06-25-13, 04:16
I think the .30 Remington that the 6.8 started with is also a good place to start. I'd say do a 6.8mm projectile in a 125-140 gr range. Since we're not confined to the standard AR length, we could add 3 to 4 more millimeters to the cartridge and maybe taper it for better feeding.
I'm not great at math, but I'd bet that could get a higher MV than the current 6.8 with better terminal ballistics and better aerodynamics (due to the longer projectile). Plus, the .30 remington case size would mean only slightly longer magazines than we currently have, and with a taper, like the AK, it wouldn't protrude as much due to the curvature.
Failure2Stop
06-25-13, 06:05
A 6.5-7mm barrier blind projectile fired from a cartridge case with about 40 gr of capacity loaded with flash suppressed, heat stable powder optimized for full burn in a 16" barrel would be about perfect. Case head should be smaller diameter than current 7.62x51mm and case length should be a bit shorter--perhaps something around .440-460 base with a 46-47mm length; maybe using polymer case technology. Even better, something like a cased telescoping 7 mm could be used.
And that's pretty much the thread right there.
Sick it in an ACR type chassis and give it three to five years in the hands of real end-users for refinement.
Typos brought to you via Tapatalk and autocorrect.
Some additional considerations - not inclusive:
Women assigned to Combat roles - weapon and round to fit them.
Role of the weapon/round - area fire, suppression, point targets and etc.
Are we designing for all terrain/climates?
Are we designing to stop wave attacks (Chinese in Korea) or something less?
Maximum effective range?
Failure2Stop
06-25-13, 08:46
Women assigned to Combat roles - weapon and round to fit them.
I see this as a non-issue. It is the duty of the individual to meet the weight requirements of the service/specialty, not to lose equipment capability due to members that cannot perform the task.
Role of the weapon/round - area fire, suppression, point targets and etc.
The role of the individual weapon is to provide accurate fire on point targets, with secondary and tertiary requirements to provide fire on area targets at extended range and to supplement machinegun fire for suppression and area denial.
Are we designing for all terrain/climates?
Why would we not?
Are we designing to stop wave attacks (Chinese in Korea) or something less?
We constantly procure items based on the last war we fought. This cannot be the driving factor in the future or we will constantly be behind the curve. However, time and time again, it has been proven that the individual and unit training level is a greater impact on success than the tools used.
[/quote]
Maximum effective range?[/QUOTE]
The "not less than" would be the current 5.56 M855 or Mk262 Mod 1. The issue is what one uses as the criteria for "max effective".
Terminal effect versus precision capability are two very different aspects of performance.
BrigandTwoFour
06-25-13, 09:03
I defer to Doc's experience on the cartridge matter. But, it looks like we're all pretty much in agreement of the bullet and case design. I really like the idea of the polymer cased ammo, which offers a lot of potential weight savings. LIke the telescoping ammo, though, has there been any issues with heat? I always thought part of the problem with caseless was that there was no ejecting brass to suck up chamber heat and carry it away from the weapon.
The issue is what one uses as the criteria for "max effective".
Terminal effect versus precision capability are two very different aspects of performance.
I think the max effective terminal effect should be around 500-600 meters, but with ammunition capable of precision reaching further if necessary. I don't think there is a need for every rifleman to reach 1000 yards (the thinking behind the 30-06), as it just doesn't appear to be a common engagement distance.
As far as fighting off "waves." I always thought that was the role of the light machine gun. But in this discussion, I think the modularity of the weapon is the key. If you need heavy automatic fire for the mission, then a heavy barreled upper and fixed stock sound appropriate. If you need light and fast, then shorter barreled upper and shorter stock.
Something I thought about last night when looking at pictures of the CZ, SCAR, and ACR is the forearm. I rather like the capability of the AR-15 to install a new forearm depending on how you want to use it (sticking support hand further out, mounting a bipod further out, recce configurations, etc).
IMO, the new rifle should have the same ability. But the forearm mounting system should be independent of the barrel nut. Perhaps an interface plate on the receiver.
IMO, the new rifle should have the same ability. But the forearm mounting system should be independent of the barrel nut. Perhaps an interface plate on the receiver.
Can't the ACR do that?
BrigandTwoFour
06-25-13, 09:26
Can't the ACR do that?
Does it? I've never gotten to handle one. I think it makes sense to do it that way.
Does it? I've never gotten to handle one. I think it makes sense to do it that way.
http://www.northeastshooters.com/vbulletin/firearms/112684-bushmaster-acr-teardown-pics.html
Seems so. I don't have one. Doesn't seem like a stretch to create after-market compatible rails that extend further forward.
BrigandTwoFour
06-25-13, 09:58
It seems that the ACR form factor is popular, with good reason. Have you seen much about the larger brother, the Massoud?
It would seem to be an ideal base platform for the cartridge we are talking about. It also uses a hybrid operating system that uses a gas tube over the barrel to impinge on a rear mounted piston, reducing the weight and reciprocating mass over the bore. An interesting concept, to say the least. Perhaps it uses the best of both worlds?
http://www.freepatentsonline.com/20100186582.pdf
http://i45.tinypic.com/sfuyjp.jpg
http://www.magpul.com/pics/massoud5.jpg
Apparently the LR-20 PMAGS were designed to work with this system. What do you all think is an acceptable number of rounds carried in a standard magazine? I know we're all used to 30 rounds in the AR-15, but the original design had 20. With the larger cartridge we're discussing, how would that affect magazine capacity?
RIFLE
While designing a new rifle, there are features of the AR that should not be discarded.
All recoil forces and the reciprocating mass in the AR is inline with each other and the bore, greatly reducing muzzle displacement.
Some designs, such as the AK and the SCAR have long protuberances from their carriers which will flex and add to muzzle displacement. The AR does not.
The true receiver of the AR is the barrel extension which allows headspacing to be set as part of the manufacturing process, eliminating the need for it to be handfitted. The result is headspace is universal to all of the rifles, not unique to each individual unit.
There is evidence that the AR handles heat very well for it's mass. The AR dumps heat through more sources than most other rifles. What other rifle comes in at 7 lbs or so and can be run as hard before it fails?
The AR bolt is it's piston. The surface which the gases act on is larger than the piston of an op rod system, has greater mass and is subjected to far less heat. Because the operating gas is at a lower temperature, the piston can be oiled which reduces carbon build up.
The AR has good rigidity reducing flex and controls harmonics increasing shot to shot consistency.
AMMUNITION
First, let's look at what the 5.56 gives us- Lighter so the warfighter can carry more within the same weight limitations. Compact for space saving. Smaller case diameter to keep magazine length short. Less taper to reduce magazine curve.
Going with a larger diameter case results in needing a longer and possibly wider magazine to retain the same capacity. Increasing case taper means the mag must curve more to accommodate the taper. A curved magazine takes up more space than a straight mag and is more difficult to pull from a pouch. Case taper isn't needed for feeding. It helps with extraction when using steel cases. Tapered cases also do not grip the chamber walls as well which increases bolt thrust and the bolt and lock up will need to be beefed up accordingly.
Larger diameter projectiles and cases means a heavier ammo load and for what gain?
I am going to raise questions in an area I am not an expert in and indeed, do not know what I do not know- the finer details of terminal ballistics.
Why is the 9mm generally preferred over the 45? Because the difference in terminal performance is marginal, 9mm uses lighter, smaller ammo and recoil is reduced.
So what really is gained by switching from a .224" projectile to a .264 - .284"? Or even .308"? Using the case size under consideration, there will be a loss in velocity and an increase in recoil. The higher velocity of the 5.56 improves bullet fragmentation. Will going to a larger, heavier projectile, larger heavier case give enough increase in terminal performance to justify the penalty? Would it not be simpler to develop a 5.56 projectile that is more lethal and allow the US to assert it meets the requirements set down by the Hague, in order to retain the advantages the 5.56 offers?
IN CONCLUSION
As we design this hypothetical new weapon, we must figure out how it will exceed the performance of the current AR.
It must be no heavier. It must have equal or better recoil management. It must be as durable and reliable. It must have better terminal performance. It must be more effective on the battlefield. It must have a simple logistical train.
There are many modern weapons and calibers designed specifically to dethrone the AR and 5.56, yet none have been able to do so. Part of that is the fact the newcomers have been able to overcome institutional inertia and labyrinthine politics. But it's also due to the fact that both the AR and the 5.56 have been through the refiner's fire of hard combat and represent the best balance of features any modern combat rifles can offer. The biggest area of improvement lays with developing a better projectile and getting our government to allow a bit more leeway as to what they'll approve as being acceptable to the Hague
SomeOtherGuy
06-25-13, 12:37
I'm not sure one cartridge for all situations makes any more sense than one camo for all terrain.
I think something like a .260 Rem or 6.5 Creedmoor (yes, nearly the same thing) would make lots of sense for infantry units in mountains or some desert situations, where a useful range of 1km+ is actually, uh, useful.
In other terrain (jungle, woodland, urban) and for non-infantry units, I would be thinking of something smaller and lighter. And the existing 5.56 NATO is probably adequate for those purposes. As would be 6.8 SPC, 300BLK, 7.62x39mm, etc.
If I had an unlimited budget for small arms for my private army, I would probably be looking at something like a SCAR-L in 6.8 SPC using the new (LWRC-related) Pmags for 6.8 SPC, as the general purpose and PDW weapon, with barrel lengths ranging from maybe 8-10" for vehicle crewmen to 14-16" or so for infantry type use.
In desert and mountains, I would be thinking along the lines of the SCAR-H or similar with that 6.5 CM type long distance cartridge.
I'm no expert in ballistics or military weapons, but purely from a civilian opinion here is my take:
1. Why not the 300BLK on an AR platform, possibly SBR like the HK416 for CQB purposes? 10-16inch barrel with AAC flash hider depending on the Unit. Anything under 150yards, the 300BLK should suffice.
Issue a specific optic with 300BLK BDC from Trijicon or Aimpoint with the rifle.
2. SCAR16/17 or AR10. If I were to choose any other caliber other than 5.56 or 300BLK, I would go straight to 7.62NATO. Effective up to 800yards if needed.
No need for any other cartridges like 6.8/6.5/7.62x39 IMO.
I'm no expert in ballistics or military weapons, but purely from a civilian opinion here is my take:
1. Why not the 300BLK on an AR platform, possibly SBR like the HK416 for CQB purposes? 10-16inch barrel with AAC flash hider depending on the Unit. Anything under 150yards, the 300BLK should suffice.
Issue a specific optic with 300BLK BDC from Trijicon or Aimpoint with the rifle.
2. SCAR16/17 or AR10. If I were to choose any other caliber other than 5.56 or 300BLK, I would go straight to 7.62NATO. Effective up to 800yards if needed.
No need for any other cartridges like 6.8/6.5/7.62x39 IMO.
There are times when you transition from close quarters to shooting across a valley before returning to base. A specialty caliber like 300blk probably isn't a good idea for general issue for that reason. Even city streets can be longer than 200 yds.
Failure2Stop
06-26-13, 06:18
6.8 is hobbled from the start. The case wants and needs a larger receiver to do the job it is being asked to do. Are there benefits to the 6.8? Absolutely. But it would do even better if given the case capacity and structural support to push more.
Militaries and special units all over are coming back to 7.62, but not because they "need" 7.62, but rather that they need more than 5.56, and it is the simplest way to achieve the increase in effectiveness and range without going to specialty ammunition. If a true intermediate cartridge solution existed, I bet that it would gain a strong following. The issue is cost versus benefit, and frankly, the cost of retooling to build a new small arm cartridge is simply not worth the benefit in the grand scheme of things. This self imposed resistance to change stifles solutions.
Typos brought to you via Tapatalk and autocorrect.
BoringGuy45
06-26-13, 07:20
6.8 is hobbled from the start. The case wants and needs a larger receiver to do the job it is being asked to do. Are there benefits to the 6.8? Absolutely. But it would do even better if given the case capacity and structural support to push more.
Militaries and special units all over are coming back to 7.62, but not because they "need" 7.62, but rather that they need more than 5.56, and it is the simplest way to achieve the increase in effectiveness and range without going to specialty ammunition. If a true intermediate cartridge solution existed, I bet that it would gain a strong following. The issue is cost versus benefit, and frankly, the cost of retooling to build a new small arm cartridge is simply not worth the benefit in the grand scheme of things. This self imposed resistance to change stifles solutions.
Typos brought to you via Tapatalk and autocorrect.
Exactly. I can't help wonder what the ballistics would be if the case were 45-47mm as opposed to 43.
Failure2Stop
06-26-13, 07:46
I just want to clarify my previous post.
I am not saying that trying to advance is futile, simply that advancement on a "better than 5.56 cartridge" has been stifled due to budget constraints.
Improving rifle/cartridge assumes a level of profiency able exploit ballistic gains; distance, accuracy, terminal effects, etc.
I do not see any need for conventional forces beyond a PIP'd M4. The weight, bulk for the individual would go past diminishing returns.. Straight into a performance penalty. For the service the logs, training, cost burden doesn't make sense.
SOF would benefit immediately, from currently being performance limited by equipment, not profiency. Also, a smaller more agile system is better placed to train equip field and sustain effectively.
I would suggest AR ergos and a similiar modular upper/lower template. 6.5mm (maybe to 7mm) has some amazing BC rounds of sufficient weight to have good terminal ballistics.
I'm digging the caseless ammo suggestion and also agree with the poster on not deviating too far from what makes the AR great (and end-user serviceable). Some kind of AR that fires 4.73×33mm caseless out of a new magazine/feed system would be my choice. A soldier could enter the battlefield with 100 rounds on tap in the same weight rifle that our troops are carrying now, with all of that familiarity on tap. The ammo has already been invented and thoroughly tested. All the money saved on brass would pay for the cost of the project after only a few years probably.
For now, caseless ammo is very expensive. When the Germans fielded the G11, cost for a single round was about $22.
Other problems include protecting the propellant from the environment, fragility and susceptibility to cook offs
For now, caseless ammo is very expensive. When the Germans fielded the G11, cost for a single round was about $22.
Other problems include protecting the propellant from the environment, fragility and susceptibility to cook offs
The LSAT is a LMG that, in one variant, uses caseless ammo. I'm not privy to all the info on the LSAT project, but if they're going to use it in a support fire role, I think the cost has at least somewhat been addresesd.
justin_247
06-26-13, 13:18
Are there benefits to the 6.8? Absolutely. But it would do even better if given the case capacity and structural support to push more.
...
Militaries and special units all over are coming back to 7.62, but not because they "need" 7.62, but rather that they need more than 5.56, and it is the simplest way to achieve the increase in effectiveness and range without going to specialty ammunition. If a true intermediate cartridge solution existed, I bet that it would gain a strong following. The issue is cost versus benefit, and frankly, the cost of retooling to build a new small arm cartridge is simply not worth the benefit in the grand scheme of things. This self imposed resistance to change stifles solutions.
I think this is an important point. While the cost of retooling an entire country (actually, more like all of Europe and North America, since we operate with NATO) is excessive, the rifle should be relatively easy to rechamber for different calibers. With this in mind, having a standard magwell that goes all the way up to 7.62x51 is very important - just swapping out the upper and installing a block means you can run every kind of ammo from .22 LR and various handgun cartridges all the way up to 7.62x51 and various shotgun cartridges.
The Colt CM901 seems like a step in the right direction to me.
As a combat veteran, I think we need to not worry about new rifles and new calibers and revert back to training true riflemen. Being able to effectively hit your target means more than anything else. Goes back to a training vs equipment argument
One issue never addressed in these threads is that the 95% of the military that doesn't shoot at the enemy has rifles that are too large. They ought to have something like a MK18 in 5.56x30. 55gr bullets at 2600fps with a 30% reduction in powder, meaning many of the downsides of an 11" barrel are reduced.
Then a machinegun in 6.5-7mm.
I would not want the machinegun and the rifle or DMR to have the same ammunition. That's a poor compromise.
BrigandTwoFour
06-26-13, 18:50
I think some posters are starting to drift off the original intent of the thread.
Of course there is real cost-benefit to better and more training time; that was never in question here. Ideally improved training would happen regardless of a new weapon acquisition.
The point of the thread is to use the advances in small arms tech and employment in the last 50 years to design a new cartridge and weapon to last another 50 years or more. It isn't a matter of should we do it or can we do it, it's simply a question of concept.
Now, back on the topic, I agree with Mistwolf in that we should preserve as many positive aspects of the M4 platform as we can, while improving the shortcomings that have appeared since the introduction of the rifle.
I am intrigued by Dano's idea of keeping the same basic form, but perhaps adjusting the dimensions and controls of the lower receiver to accomodate a slightly lengthened cartridge.
As far as cartridges go, I do think its time for an improvement. The 5.56 does well with exactly what it was designed to do: killing unarmored targets on open ground within 300 yards (and particularly well within 100). Combined with a good barrier blind or expanding bullet, it's an ideal civilian and LE round.
But those high performing bullets are not usually in compliance with LOAC for military rounds. But the little FMJ .223 was not designed with shooting through auto glass, or firefights in the mountains of Afghanistan, in mind. In order to get the same benefits of range, barrier penetration, and terminal effect, I think a slightly larger bullet is required.
BrigandTwoFour
06-26-13, 18:53
One issue never addressed in these threads is that the 95% of the military that doesn't shoot at the enemy has rifles that are too large. They ought to have something like a MK18 in 5.56x30. 55gr bullets at 2600fps with a 30% reduction in powder, meaning many of the downsides of an 11" barrel are reduced.
Then a machinegun in 6.5-7mm.
I would not want the machinegun and the rifle or DMR to have the same ammunition. That's a poor compromise.
I get not wanting the LMG to share the same ammo as the rifles. But why not have the rifles and the DMR share the same ammo? I could be wrong, but the whole point of the rise of the DMR platform was that the common infantry rifle was not up to the task it was being asked to perform. As a compromise between the standard issue rifle and the ability of a sniper, the DMR was born to give some extended range to a squad. Is that incorrect?
To me, the ideal DMR concept is more about configuration of barrel and optic than a completely different platform and cartridge.
Is there really anything wrong with 5.56 as an assault rifle cartridge? (serious question)
The commercial sector needs to get on the ball with caseless.
wild_wild_wes
06-26-13, 22:49
One issue never addressed in these threads is that the 95% of the military that doesn't shoot at the enemy has rifles that are too large. They ought to have something like a MK18 in 5.56x30. 55gr bullets at 2600fps with a 30% reduction in powder, meaning many of the downsides of an 11" barrel are reduced.
Then a machinegun in 6.5-7mm.
I would not want the machinegun and the rifle or DMR to have the same ammunition. That's a poor compromise.
I get not wanting the LMG to share the same ammo as the rifles. But why not have the rifles and the DMR share the same ammo? I could be wrong, but the whole point of the rise of the DMR platform was that the common infantry rifle was not up to the task it was being asked to perform. As a compromise between the standard issue rifle and the ability of a sniper, the DMR was born to give some extended range to a squad. Is that incorrect? To me, the ideal DMR concept is more about configuration of barrel and optic than a completely different platform and cartridge.
I think that is the answer right there.
5.56x30 souped-up PDW for general issue.
6.5-7mm intermediate round for DMR/LMG
plus
.338 for MG/Sniper
One issue never addressed in these threads is that the 95% of the military that doesn't shoot at the enemy has rifles that are too large. They ought to have something like a MK18 in 5.56x30. 55gr bullets at 2600fps with a 30% reduction in powder, meaning many of the downsides of an 11" barrel are reduced.
I think that is the answer right there.
5.56x30 souped-up PDW for general issue.
I think an area of future growth is the VSBR / PDW.
This is the 8.5" -11.5" weapon.
The driver behind this is the concept of "handiness tumps nearly everything".
In order to perform adequately in the short barrel, a different cartridge than 556 is required.
556 is great in 16-20" barrels, but starts to be non-optimal shorter than this.
Even in the latest greatest bonded ammo, bullet expansion is only 2/3rds of what is possible in larger calibers.
The 300 does very well in an 8.5", but gains only ~100 fps moving up to a 16".
IMO, this limits the flexiblitiy of the 300 as you always get SBR performance.
Barrier punching and penetration seem to be excellent though.
The 6.8 does well in 8.5" ( 90 gr @ 2450 fps ) and very well in 16" ( 90 gr @ 2850 fps ).
Barrier punching and penetration are also generally excellent.
Recent testing of the XM68GD, show that a 8.5" barreled weapon can penetrate a windshield and 2 hogs with good expansion at 200 yards.
Maximum expansion at closer ranges is up to .64", which produces a large wound cavity.
That is a lot of punch in a small package.
For door kickers and face shooters, the 16 version offer a significant increase in effective range.
I get not wanting the LMG to share the same ammo as the rifles. But why not have the rifles and the DMR share the same ammo? I could be wrong, but the whole point of the rise of the DMR platform was that the common infantry rifle was not up to the task it was being asked to perform. As a compromise between the standard issue rifle and the ability of a sniper, the DMR was born to give some extended range to a squad. Is that incorrect?
To me, the ideal DMR concept is more about configuration of barrel and optic than a completely different platform and cartridge.
I don't have enough experience to know what the ideal layout for Infantry is. I do have reason to believe that an Infantry unit loses a LOT more when they trade 210 rounds of 5.56mm for 110 rounds of 7x46 than they gain when they add in the extra 200 yards of range they pick up. Obviously it is a logistical issue but so far issuing M80 and AA53 instead of M855 to certain members of the squad has worked.
In any case, COIN thrusts rifles to the forefront but in MCO rifles will account for maybe 5-10% of enemy casualties caused by ground forces.
BrigandTwoFour
06-27-13, 09:28
I agree that the short PDW has been having a larger role to play. But designing solely on that requirement is focusing too much on the "the last war fought" rather than the totality of possibilities.
I think it makes more sense to design a cartridge that is very capable from a variety of barrel lengths. Using the M4 program as a model, again, we have the Mk18 upper and the Mk12 upper receiver programs. I don't see why we shouldn't think more along those lines rather than think about a dedicated length.
As far as capacity goes, I agree as well. Part of the appeal of going to 5.56 over 7.62 was the ability to nearly triple the amount of ammunition carried. I think there is a compromise to me had. I don't think we should be talking about reducing from 210 to 110, but rather 210 to 180 or so. A slightly larger bullet in a slightly larger cartridge still wouldn't weigh as much as 7.62, especially if we pursue Doc's idea of the polymer casing (saving nearly 30% weight over brass).
I agree that the short PDW has been having a larger role to play. But designing solely on that requirement is focusing too much on the "the last war fought" rather than the totality of possibilities.
Like I said though, this would have been handy in the last war, but REALLY handy in the next one (if it's a major fight).
One issue never addressed in these threads is that the 95% of the military that doesn't shoot at the enemy has rifles that are too large. They ought to have something like a MK18 in 5.56x30. 55gr bullets at 2600fps with a 30% reduction in powder, meaning many of the downsides of an 11" barrel are reduced.
Then a machinegun in 6.5-7mm.
I would not want the machinegun and the rifle or DMR to have the same ammunition. That's a poor compromise.
Same concept as M1 Carbine to supplement the M1 Garand like in WWII.
I'm suggesting staying with AR-type ergonomics. Be it a scaled up AR. Scaled up KAC PDW, RemMPG ACR, etc.
Modular uppers to allows for easy logs, and specialized upper development. I find a one lower, multiple upper, solution is less weigh/bulk to lug around.
There are times when you transition from close quarters to shooting across a valley before returning to base. A specialty caliber like 300blk probably isn't a good idea for general issue for that reason. Even city streets can be longer than 200 yds.
300BLK is capable past 200yards, you just have to adjust for the drop depending on the bullet (around 8" for 115gr). But for CQB and anything under 200yards, it will suffice.
For greater distances, thats why they have DMR's in larger calibers like 7.62NATO. 5.56 is basically in between the two calibers that offers a balance of both capacity and range.
Davetrader
07-01-13, 15:23
My experience is in finance and I shoot for fun. I don't know what the professionals on here think of Travis Haley or his comment that he found the recoil on 6.8SPC to be slowing him down. It seems to me that most of the cartridges suggested would have the same or more recoil.
Why not neck up 223 to .257-.277? 7.62x40(his login on Ar15.com) has done a number of wildcats including a 6.8x40 and a 25x40. I believe his 6.8 wildcat was getting 2800-2900fps from a 16" barrel with the 80gr TSX and the 25x40 was doing 2500fps with a 100gr SMK.
Would this not provide better terminal performance and barrier penetration with less recoil than other suggested calibers while minimizing costs, changes, and weight? It could be paired with a Mk318 style bullet tuned to whatever velocity is needed.
The more the projectile weighs, the more recoil.
Travis whoever may feel a 6.8 "slows him down" while shooting notional paper drills inside of 50m on a square range.
Many highly experienced persons, who can choose, are moving to 7.62 carbines for the enhanced ability to "slow down" targets that shoot back. Even with the weight, bulk, and recoil penalty.
In addition to greatly enhanced terminal ballistics, with a viable sustainment training regime and modern optic suite, 800-1000m isn't really that difficult with a 7.62 carbine.
But, can we get there with a lighter faster shooting carbine?
Davetrader
07-01-13, 22:35
Travis whoever may feel a 6.8 "slows him down" ....
Many highly experienced persons, who can choose, are moving to 7.62 carbines for the enhanced ability to "slow down" targets that shoot back. Even with the weight, bulk, and recoil penalty.
In addition to greatly enhanced terminal ballistics, with a viable sustainment training regime and modern optic suite, 800-1000m isn't really that difficult with a 7.62 carbine.
But, can we get there with a lighter faster shooting carbine?
I mention him only because I believe he can shoot half way decently and if it slows him down, then it would no doubt slow the average soldier down who doesn't get nearly the range time he does.
How can we make a lighter faster shooting carbine by going to larger cartridges? That is exactly why I referenced him and the 6.8. I'm not understanding why we need to go bigger. I can understand bumping the mag length out to allow for seating longer bullets. Is adding 200fps to the 6.8SPC by going out to 45mm really going to be an improvement that matters?
I resubmit kurt's 6.8x40 223 wildcat.
""16" 1:10 barrel 20 round string average with 26.2gr of 1680 and the 85gr Barnes = 2,960 fps"
It doesn't roll even with 6.8SPC or a 6.5-7x45-47mm cartridge but it would seem to get the job the done with the minimal amount of weight gain, recoil, loss of capacity, etc.
A 6.5-7mm barrier blind projectile fired from a cartridge case with about 40 gr of capacity loaded with flash suppressed, heat stable powder optimized for full burn in a 16" barrel would be about perfect. Case head should be smaller diameter than current 7.62x51mm and case length should be a bit shorter--perhaps something around .440-460 base with a 46-47mm length; maybe using polymer case technology. Even better, something like a cased telescoping 7 mm could be used.
260 Rem fits other than being the same case head size as 762x51.
Incredibly accurate, 142gr SMK and 37gr of varget has a 6in group for me at 1000. I'm sure the terminal on target ballistics are effective as well
260 is too big a case for a 16" barrel.
BrigandTwoFour
07-01-13, 23:31
How can we make a lighter faster shooting carbine by going to larger cartridges? That is exactly why I referenced him and the 6.8. I'm not understanding why we need to go bigger. I can understand bumping the mag length out to allow for seating longer bullets. Is adding 200fps to the 6.8SPC by going out to 45mm really going to be an improvement that matters?
I would argue that the goal is NOT to produce a lighter faster shooting carbine, but one that is more effective through intermediate barriers like auto glass while simultaneously offering better terminal ballistics at intermediate ranges.
I resubmit kurt's 6.8x40 223 wildcat.
""16" 1:10 barrel 20 round string average with 26.2gr of 1680 and the 85gr Barnes = 2,960 fps"
It doesn't roll even with 6.8SPC or a 6.5-7x45-47mm cartridge but it would seem to get the job the done with the minimal amount of weight gain, recoil, loss of capacity, etc.
I've seen similar wildcats out there like the 6.5 PCC as well that seem interesting. But, and this is just my opinion based on what I've read historically and from AARs, a larger bullet in the range of 120-130 grains offers much improved energy transfer to the target. Taking a 85 gr Barnes to 2900 fps is is not much different than using a 77 gr SMK in the current MK 262 loading.
I actually read an account today from Teddy Roosevelt's assault on San Juan hill in Cuba. He observed that the Spanish 7mm Mausers offered better accuracy and range due to the higher velocity and lighter spitzer point bullets. In contrast, the American Krag rifles fired a larger heavier 220 round nosed bullet. Teddy observed that the Krag, when it made impact, caused devastating damage to the target. The Mauser, in contrast, created a hole that often resulted in a clean pass through, requiring hits in vital areas to put the target down. Still, the superior accuracy and range of the Mauser proved superior in that battle.
Obviously, that sounds an awful lot like the 9mm vs .45 debate.
The bottom line being, we should be looking for an appropriate balance between range, projectile size/weight/ and controllability. What is the right answer? I don't know. I can offer my theories, but I don't have the real world experience to back it up. But I woud guess the current best answer lies somewhere in the pattern of cartridge Doc mentioned.
Would a 6mm or .257 bullet offer enough of an improvement from the .224 to be worthy of consideration? I know each has some drawbacks. However, the BC could be improved from the .224 to improve distance. I know the .257 Roberts I used to hunt mule deer would put them down quick and recoil was light.
Neck down the 6.8 spc? Would that improve reach and terminal ballistics and keep recoil down?
I think there's only going to be a change to something new when someone starts fresh, from ground up.
New more efficient propellants, new case material or even better, if possible caseless design and cutting edge materials for the firearm itself.
Then, we can start from scratch. Make a study to find the best balance between terminal/external ballistics and weight/recoil. Make a new intermediary cartridge based on the results of the study and then build a new rifle/carbine around that.
Any attempt to bring intermediary cartridges to the military, with today's weapons, case design and materials, will meet strong resistance from multiple parties because the weight of the rifle and ammo will go up quite a bit.
LSAT would be a good tool to get there, but everything is moving so slow, I doubt we'll see anything come out of it in the next ten years.:suicide:
Grand58742
07-02-13, 18:13
Not seeing a lot of Grendel love here. Besides not really taking off (which I attribute to the initial lack of SAAMI spec and being selective about the manufacturers) and requiring a slightly longer barrel to achieve better ballistics, is it really that bad a cartridge? Are the terminal ballistics on par with the 6.8? I know the accuracy and downrange performance is reported to be better overall, just unsure of terminal ballistics.
- Common upper receiver chasis that accepts calibers up to 7.62x51
- Upper with modular fore end, removable and replaceable allowing various rail lengths to accommodate various barrel/gas system lengths
- Non reciprocating charging handle that is interchangeable on either side of the rifle
- Caliber conversions for 5.56x45, 7.62x39, 300 BO, and 7.62x51. I think these three satisfy all possible current needs. Having a chasis that can accommodate up to 7.62x51 will allow it to handle any new intermediate caliber that is later developed. For now, 5.56x45 and 7.62x51 are fine for general issue, with 7.62x39 and 300BO reserved for special applications.
- Cold hammer forged barrels
- Barrels removable/replaceable with simple tools at armorer level. I'm on the fence re: QC. Steyr got it right 35 years ago with the AUG. if this can be adapted to a new system, it would work well I feel. But a non-QC barrel would simplify (and lessen costs) the system.
- Operating system based on AR18, but would enlarge the bolt for all calibers to make it more robust
- Possibly use the Massoud gas system with its short stroke piston closer to the breech with a long AR-esque gas tube extending from the gas block to the piston
- Lower receiver with AR15 ergos and controls, albeit with ambi controls. Ambi bolt release similar to updated G36 bolt release ( which is similar to FAL and Robarms)
- Folding and collapsing stock
- Interchangeable mag wells allowing various magazine options for various calibers
A beefed up ACR that is done correctly would probably fit the bill.
BrigandTwoFour
07-02-13, 22:16
Not seeing a lot of Grendel love here. Besides not really taking off (which I attribute to the initial lack of SAAMI spec and being selective about the manufacturers) and requiring a slightly longer barrel to achieve better ballistics, is it really that bad a cartridge? Are the terminal ballistics on par with the 6.8? I know the accuracy and downrange performance is reported to be better overall, just unsure of terminal ballistics.
I don't think the Grendel is bad, but it is a compromise cartridge designed to fit the long skinny 6.5 into the AR-15 magazine well. With the performance of cartridges like the .260, 6.5 Creedmoor, and the rather legendary 6.5x55 representing what the round is capable of, the Grendel just seems....mediocre. But that doesn't mean its a bad round.
The point of this discussion is to determine an ideal intermediate cartridge and a rifle to house it. I think the 6.5 run in a cartridge larger than can fit in the AR-15, but smaller than one requiring an AR-10 could be a great performer.
I don't think the Grendel is bad, but it is a compromise cartridge designed to fit the long skinny 6.5 into the AR-15 magazine well. With the performance of cartridges like the .260, 6.5 Creedmoor, and the rather legendary 6.5x55 representing what the round is capable of, the Grendel just seems....mediocre. But that doesn't mean its a bad round.
The point of this discussion is to determine an ideal intermediate cartridge and a rifle to house it. I think the 6.5 run in a cartridge larger than can fit in the AR-15, but smaller than one requiring an AR-10 could be a great performer.
6.5 wildcat based off the .250 savage or .22-250? Isn't the 6xc based on the .22-250?
6.5 wildcat based off the .250 savage or .22-250? Isn't the 6xc based on the .22-250?
it's called the 6.5 creedmoor, i vote neck it up to 7mil standard load should be a 115 grain flat base spitzer at 2700. and yes the 6xc is based off of the 250 savage as is the 6.5 creedmoor
There is a whole lot of lunacy in this page.
Anything with a bolt face larger than a 6.5G is too damn big. Caliber conversions are retarded because Soldiers aren't going to switch between different calibers. They'll be issues one kit and left alone.
Kind of curious, but does anyone have statistics of how many are killed on a modern battlefield with small arms vs CAS / indirect fire / crew served weapons?
Traditionally in major combat operations you can expect 80-90% of casualties to be inflicted with high explosives. Rifles are window dressing, inflicting at best a single digit percentage of casualties.
Traditionally in major combat operations you can expect 80-90% of casualties to be inflicted with high explosives. Rifles are window dressing, inflicting at best a single digit percentage of casualties.
What about in the current COIN environment? Still 80-90%? IEDs are the primary contributor for coalition casualties for sure.
Perhaps it would be interesting to design a new small arm/ammo combination without the limitations of the Hague Conventions.
I don't have studies to point back to but it's still heavily in favor of HE. A friend was a nurse in the ICU in Baghdad during the surge and reports seeing next to no small arms injuries--all explosives whether our doing or theirs.
There is a whole lot of lunacy in this page.
Anything with a bolt face larger than a 6.5G is too damn big. Caliber conversions are retarded because Soldiers aren't going to switch between different calibers. They'll be issues one kit and left alone.
Caliber conversions make sense for special end users, not for general issue. Not sure if you are referring to my suggestion about the bolt face. I am suggesting that the entire bolt be made larger, most specifically the bolt lugs, assuming this would be a Stoner-pattern multi-lugged bolt.
BrigandTwoFour
07-03-13, 09:07
Kind of curious, but does anyone have statistics of how many are killed on a modern battlefield with small arms vs CAS / indirect fire / crew served weapons?
I'm not so sure about these days. But in WWI, it was upwards of 75% casualties due to artillery and the like. Relatively few from small arms.
I could see it either way in today's terms. Maneuver until you can pin down the enemy and call in CAS or indirect makes a lot of sense. But I have no doubt that our potential future enemies are watching and taking notes. Future conflict may take place in much more populated areas where the risk of collateral damage is too high to use CAS or indirect, thus necessitating more small arms.
wild_wild_wes
07-03-13, 10:54
it's called the 6.5 creedmoor, i vote neck it up to 7mil standard load should be a 115 grain flat base spitzer at 2700. and yes the 6xc is based off of the 250 savage as is the 6.5 creedmoor
A 7mm cartridge combat load would be almost as heavy as a 7.62 NATO load. Way too heavy.
I'm not so sure about these days. But in WWI, it was upwards of 75% casualties due to artillery and the like. Relatively few from small arms.
I could see it either way in today's terms. Maneuver until you can pin down the enemy and call in CAS or indirect makes a lot of sense. But I have no doubt that our potential future enemies are watching and taking notes. Future conflict may take place in much more populated areas where the risk of collateral damage is too high to use CAS or indirect, thus necessitating more small arms.
I hate to say it but, Rules of War apply when you plan on being chivalrous. Germans, Japanese and Russians didn't hesitate to bomb cities. (Heck even us in WW2) It was something of, "We're here to win wars and if they want to park themselves in cities, we'll bomb cities."
I mean, I really think that larger assemblies of vehicles and machines changed war. It's been this way a long time too.
Alexander the Great conquered the known world by Cavalry. Tanks and Aviation revolutionized the way War was done from WW1 to WW2. MG's and artillery revolutionized the way war was done in WW1.
Before that Cannons and Cavalry dominated the battlefields.
Before that Siege weapons and warfare dominated.
I think what we found was that marksmen while critical, aren't what are winning wars, certainly helping but, anyway just my inexperienced $.02. I'm not a soldier, never have been, never claimed to be.
I just think that things like tanks and really Air Superiority are going to be more effective for us winning wars than a cartridge that has 200m more effective range out to say 500m than what we currently issue to be effective at 300m.
I also think the grass is always greener. But just something to keep perspective on.
You know what will motivate us to change? Something to come and kick the crap out of what we currently have.
I mean like Russian Ak47 from Mosin Nagant.
The STG44 rolled out and changed the game. Anyway, I'm rambling.
The Steyr ACR from the 80's was a downward ejecting bullpup that fired a plastic telescope cased flachette round.
Check out this short video that covers it very well in some technical detail and shows the down.
http://www.youtube.com/watch?v=9Ltga6RhDjc
I think the compactness offered by a bullpup combined with the downward ejection that is somewhat facilitated by pushing the CT round into the chamber is a great idea.
I just think changing from a CT flachette to a CT 6.5mm round is really the way to go knowing what we know now.
Bullpup solves the compactness problem that you need to have in vehicles and urban warfare. Downward ejection solves the bullpup problem. They just need to get the IWI X95 ergos (M16 fire controls and M16 mag release) with the rigid trigger plate of the SAR21. Go full flat top rail and cover the handguard in keymod holes.
I think the 6.5's are the way to go. They are a perfect balance of low recoil, compact size and great ballistic coefficients. They penetrate well, and have enough velocity to reach out beyond 700 yards. They are taking over in long range shooting competitions, and anyone who has hunted with a 260 rem or 6.5 Creedmore know they will do the job.
.270 is not a bad idea in something like a 270-08, but I don't think as much research and development has been done with that caliber. The 6.8SPC doesn't have the BC and reach that the 6.5's have, even the 6.5 Grendel. The bigger 270 Winchester is bulky and doesn't have as many high BC bullets developed for it, as it is not traditionally a target cartridge. The 270-08 has existed for some time as a wildcat, so someone may have more information on it.
The 300 Blackout is ridiculous for a general purpose rifle caliber, and I think the fact that you can't deer hunt in most states with a 223/556 should tell us something about that one too.
BrigandTwoFour
07-03-13, 18:54
I think the 6.5's are the way to go. They are a perfect balance of low recoil, compact size and great ballistic coefficients. They penetrate well, and have enough velocity to reach out beyond 700 yards. They are taking over in long range shooting competitions, and anyone who has hunted with a 260 rem or 6.5 Creedmore know they will do the job.
But the question comes back to this: how relavent is performance in long range shooting competitions out of hot rodded 6.5s to military usage?
I'm not knocking the 6.5 bullet. But, IMO, when we start talking about how the 6.5 has better BC and performance in long range competition, I think we're going down the wrong path.
Remember, the vast majority of engagements happen within 100 yards, and most of the rest within 300 with an occasional need to hit at 500-600. Those guys winning those competitions with the 6.5 bullets are also running barrels that are 24+ inches long. How much ability does the 6.5 maintain as we shorten a barrel down to say 10.5"? Choosing a cartridge on its ability to hit at 1000+ yards is old-world thinking that brought us the Springfield 1903. It was a great weapon, no doubt, but combat tactics have changed.
I think most of us are talking about 6.8 and 6.5 bullets of roughly the same weight (110-130 grains). I don't think there is a performance gap between those two significant enough at the ranges and barrel lengths we're talking to really warrant an argument about it. I think the question may come down which bullets feed better when run through an automatic weapon or potentially from a belt fed weapon.
I hate to say it but, Rules of War apply when you plan on being chivalrous. Germans, Japanese and Russians didn't hesitate to bomb cities. (Heck even us in WW2) It was something of, "We're here to win wars and if they want to park themselves in cities, we'll bomb cities."
You are right, of course, war is hell. But When was the last time any major country has elected to bomb an entire city since the advent of precision weapons? Technology changes how warfare is conducted.
I would argue that the continued evolution of precision munitions offers outstanding war-winning capability, but does little when your enemy decides to hide among an innocent population (and this is coming from an Air Force guy). Small arms will always have their role in direct action and the need to kill the enemy face to face.
Studies showed that the greatest factor in winning that face to face confrontation was how long a combatant was exposed and how quickly shots (especially multiple shots) could be accurately fired at the combatant in that time. The 7.62x51 proved too slow for the latter.
The 5.56 has proven excellent in that regard, but I think history will show that the penetration of the round through barriers and reliance on yaw for terminal effect has been its greatest weaknesses. New developments in bullet construction have mitigated this in some respects, but those bullets are not often available due to LOAC concerns.
Thus, I come back to the search for a new intermediate cartridge that offers a balance of speed on target with the need for penetration and incapacitating power at ranges in the 300-500 range. Historically, whenever a new cartridge is developed, a new weapon is developed with it (30-03/06 for the Springfield, .308 for the M14, 5.56 for the M16, etc)
Heavy Metal
07-03-13, 19:14
What was DocGKR's ideal cartridge that came out of the 6.8 development? The 7mm Murphy I believe.
So, the works been done, just needs production and a rifle.
Caliber conversions make sense for special end users, not for general issue. Not sure if you are referring to my suggestion about the bolt face. I am suggesting that the entire bolt be made larger, most specifically the bolt lugs, assuming this would be a Stoner-pattern multi-lugged bolt.
The bolt does have to be larger for 6.5, because the bolt thrust of the larger case limits operating pressure. The problem is weight, both of rifles and ammunitions. Magazines as well.
Caliber conversions don't even make sense for special operations. By the time you have separate optics, conversion parts, etc you aren't saving a significant amount of money over a new rifle, and since these things will end up in the arms rooms (or an Operators conex) anyway it might as well be a whole rifle.
What was DocGKR's ideal cartridge that came out of the 6.8 development? The 7mm Murphy I believe.
So, the works been done, just needs production and a rifle.
Remember, the vast majority of engagements happen within 100 yards, and most of the rest within 300 with an occasional need to hit at 500-600.
I think most of us are talking about 6.8 and 6.5 bullets of roughly the same weight (110-130 grains).
Studies showed that the greatest factor in winning that face to face confrontation was how long a combatant was exposed and how quickly shots (especially multiple shots) could be accurately fired at the combatant in that time. The 7.62x51 proved too slow for the latter.
The 5.56 has proven excellent in that regard, but I think history will show that the penetration of the round through barriers and reliance on yaw for terminal effect has been its greatest weaknesses. New developments in bullet construction have mitigated this in some respects, but those bullets are not often available due to LOAC concerns.
Thus, I come back to the search for a new intermediate cartridge that offers a balance of speed on target with the need for penetration and incapacitating power at ranges in the 300-500 range. Historically, whenever a new cartridge is developed, a new weapon is developed with it (30-03/06 for the Springfield, .308 for the M14, 5.56 for the M16, etc)
I feel strongly that the 6.8x43 meets the requirement of excellent terminal performance out to 300 and ability to make hits out to 500-600.
It combines the speed on target of 556 with excellent short barrel performance.
It retains 30 round capacity polymer magazines ( PMAG68 ) in an easy to handle form factor only slightly larger than 556.
With 90 grain bonded bullets, the magazines are slightly heavier than 556, allowing 6 magazines of 6.8 for the same weight as 7 magazines of 556.
New bullet advances like bonded and TSX allow light for caliber bullets to produce excellent results relative to heavier fragmenting designs.
IMO, The 7mm Murray is a great concept, but gives up many of the handiness advantages of the slightly less powerful 6.8.
Alexander the Great conquered the known world by Cavalry.
Alexander conquered most of the known (to Europe) world through the use of combined arms. Macedonian infantry were every bit as important as companion cavalry in the phalanx. You can't have "hammer and anvil" without an anvil.
I feel strongly that the 6.8x43 meets the requirement of excellent terminal performance out to 300 and ability to make hits out to 500-600.
It combines the speed on target of 556 with excellent short barrel performance.
It retains 30 round capacity polymer magazines ( PMAG68 ) in an easy to handle form factor only slightly larger than 556.
With 90 grain bonded bullets, the magazines are slightly heavier than 556, allowing 6 magazines of 6.8 for the same weight as 7 magazines of 556.
New bullet advances like bonded and TSX allow light for caliber bullets to produce excellent results relative to heavier fragmenting designs.
IMO, The 7mm Murray is a great concept, but gives up many of the handiness advantages of the slightly less powerful 6.8.
Makes sense.
When you unlock the 6.8 from the confines of the AR mag well and create a dedicated lower you can unleash the potential of this round.
Does anybody know what's become of LWRC's UCIW SIX8 sub-carbine?
how relavent is performance in long range shooting competitions out of hot rodded 6.5s to military usage?
I'm not knocking the 6.5 bullet. But, IMO, when we start talking about how the 6.5 has better BC and performance in long range competition, I think we're going down the wrong path.
Remember, the vast majority of engagements happen within 100 yards, and most of the rest within 300 with an occasional need to hit at 500-600. Those guys winning those competitions with the 6.5 bullets are also running barrels that are 24+ inches long. How much ability does the 6.5 maintain as we shorten a barrel down to say 10.5"?
Shorten it down as much as you want, it still outperforms the .556, and the ballistic coefficient is still greater than anything you can shoot out of a 6.8spc. Given your 100-300 yard logic, we might as well drop back to the 7.62x39 round. I thought one of the basic ideas here was that some of the combat ranges have INCREASED over in the sand box... Am I missing something? I don't see the need for anything new if we are still talking 100-300 yards. Just stick with the M4 and .556.
If you look at what has happened to the .556 round over the years, the weight of the bullets we have been shooting has slowly increased. The 62 grain, and now 77 grain bullets are designed for longer range (better BC), less wind drift, and better penetration. Those advancements came from long range shooting competitions.
Both the 6.8spc and 6.5 Grendel would increase effective stopping power at 0-300 meters, but beyond that, the 6.5 performs much better with its better ballistic coefficients and higher velocities. Why would you choose the one that did only ONE thing well? After adoption, we would obviously try to squeeze every ounce of distance out of it we could, while lessening wind drift etc. The 6.5 Grendel simply has more potential.
BoringGuy45
07-04-13, 10:59
While I think something like the 7mm Murray would be the ideal intermediate cartridge in terms of external and terminal ballistics and recoil, I wonder if the weight and size might be an issue.
If I remember correctly, for the trials that led to the creation of the 6.8, 6, 6.5, 6.8, 7, and 7.62mm rounds were first considered. The 6.5 had the best external ballistics, the 7mm had the best terminal ballistics, and the 6.8 was a good compromise between the two.
I can't help but wonder if similar results would be found if the 6.5 Grendel was necked up to 6.8mm. I guess there was some guy on arfcom and the 6.8 forums who played around with this, but I haven't seen anything recently. I wonder if the shorter, fatter case of the Grendel would mean about the same (or better) terminal ballistics as the 6.8 SPC in a 115-120 gr package, but the shorter case would allow for longer bullets, meaning better BC. This could mean better terminal ballistics than the 6.5 Grendel but better external ballistics than the 6.8 SPC.
No way you are going to stuff a bigger bullet into the Grendel case and get higher ballistic coefficient without losing so much velocity that you are back don into 7.62x39 territory. I mean, if you look at the SPC and 7.62x39, there is not THAT much difference in velocity.
7.62x39 - 123gr bullet @ 2400fps (bc .295)
6.8 SPC - 120gr bullet @ 2500fps (bc .400)
6.5 Grendel - 120gr bullet @ 2650fps (bc .510)
I can find practically zero information on the 7mm Murray you mentioned. Tell me about it....
BrigandTwoFour
07-04-13, 11:55
I can find practically zero information on the 7mm Murray you mentioned. Tell me about it....
https://www.m4carbine.net/showthread.php?t=19936
and
https://www.m4carbine.net/showthread.php?p=523298
It's by the guys who came up with the 6.8 SPC.
BoringGuy45
07-04-13, 11:58
I can find practically zero information on the 7mm Murray you mentioned. Tell me about it....
It's right now no more than a concept cartridge and in reality, I don't think anyone here thinks it's ever going to be any more than that. Ballistically, it's basically a universal cartridge: Better range and terminal ballistics than the 5.56 but lighter, smaller, and less recoil than the 7.62 NATO. It would give riflemen a longer, harder punch but it would increase weight and decrease ammo that could be carried, but it would certainly increase what machine gunners could carry.
No way you are going to stuff a bigger bullet into the Grendel case and get higher ballistic coefficient without losing so much velocity that you are back don into 7.62x39 territory. I mean, if you look at the SPC and 7.62x39, there is not THAT much difference in velocity.
7.62x39 - 123gr bullet @ 2400fps (bc .295)
6.8 SPC - 120gr bullet @ 2500fps (bc .400)
6.5 Grendel - 120gr bullet @ 2650fps (bc .510)
That's still a pretty good BC for the 6.8. In a longer, streamlined bullet, it would improve.
BrigandTwoFour
07-04-13, 12:33
Both the 6.8spc and 6.5 Grendel would increase effective stopping power at 0-300 meters, but beyond that, the 6.5 performs much better with its better ballistic coefficients and higher velocities. Why would you choose the one that did only ONE thing well? After adoption, we would obviously try to squeeze every ounce of distance out of it we could, while lessening wind drift etc. The 6.5 Grendel simply has more potential.
If you think that is what is needed, then I would say you are justified. But my original criteria was vastly better penetration and terminal effect from 0-300 and better terminal effect at 500.
Running some off the calculations on JBM....
This is a 6.5 123gr SMK running at 2750 FPS (what I would think is reasonable for the barrel lengths we're talking about)
http://img.photobucket.com/albums/v144/disposablehero/65123smk2750fps.png
This is a 6.8 135gr SMK at 2700 FPS
http://img.photobucket.com/albums/v144/disposablehero/68135smk2700fps.png
At the ranges we are realistically taking about (0-500), there is very little difference between these two. In fact, they are almost identical all the way out to 1000 yards.
But they are both vastly superior to 5.56. For reference, this is 5.56 77gr SMK at 2750
http://img.photobucket.com/albums/v144/disposablehero/77grSMK2750.png
So, coming back to an earlier point, I think either route is fine on paper here. But Doc's research shows that the 6.8 disrupts faster in soft tissue, thus causing more damage. I think the sectional density of the 6.5 was a minus in that regard. In any case, IMO, either one would be fine in a slightly larger cartridge. I think both could be loaded to the same slightly larger mag length and be run in the same rifle.
No way you are going to stuff a bigger bullet into the Grendel case and get higher ballistic coefficient without losing so much velocity that you are back don into 7.62x39 territory. I mean, if you look at the SPC and 7.62x39, there is not THAT much difference in velocity.
7.62x39 - 123gr bullet @ 2400fps (bc .295)
6.8 SPC - 120gr bullet @ 2500fps (bc .400)
6.5 Grendel - 120gr bullet @ 2650fps (bc .510)
These are on target for heavy, long range DMR loads @ 16".
Lighter bullets at higher velocity give you flatter trajectory and less lead on a moving target in the 0-300 range.
6.8 SPC 16" bbl - 90gr bullet @ 2850fps (bc .236)
What do x39 and 6.5 have available for high velocity loadings?
I think the answer is NONE, but I haven't looked into it.
Short barrel performance.
6.8 SPC 8.5" bbl - 90gr bullet @ 2450fps (bc .236)
What do x39 and 6.5 have available for very short barrel loadings?
Again, I think the answer is standard loads and hope for the best, but I haven't looked into it.
It is this flexibility, or good performance across a variety of conditions that gives 6.8 the win over 5.56,6.5 and x39 in internal and external ballistics.
Again, numbers don't drop targets.
Shot placement and barrier/terminal performance do.
Grand58742
07-04-13, 13:48
So, coming back to an earlier point, I think either route is fine on paper here. But Doc's research shows that the 6.8 disrupts faster in soft tissue, thus causing more damage. I think the sectional density of the 6.5 was a minus in that regard. In any case, IMO, either one would be fine in a slightly larger cartridge. I think both could be loaded to the same slightly larger mag length and be run in the same rifle.
The reason I brought up the 6.5G to begin with was looking at the potential for a DMR rifle as well as a carbine, like the Mk12 is to the M4. It's true the 6.5G needs a longer barrel for better ballistics (18+ inches) however, that length being not optimal for urban applications and CQB. However, seeing what the terminal ballistics are within 300-400 meters for a 14.5 or 16 inch barrel are for the 6.5 vs the 6.8 (pretty even according to your charts) but wondering how much that changes at range with a longer barrel in a 6.5G in a DMR type platform in open areas like Afghanistan. Danno said multiple uppers might be the best way of going and I think he might be on to something there. Hence, the Grendel might be a little better overall than the 6.8 especially at range.
From the Alexander Arms website, the Grendel likes a longer barrel and gets far better ballistics at range with 20 inches or more. Which tends to be close to the DMR length in current issued rifles. I'm going to assume (yeah, I'm wrong for doing so) an SBR/CQBR type setup like a Mk18 is going to give up a lot ballistically, but we aren't talking about long range shots here with that kind of weapon and the trade off of barrel length compared to accuracy might be acceptable in my opinion.
I know the conversation is about a service rifle, but the fact that the M16 FOW is and has been used from everything from SMGs up to DMR/precision setups. And any new caliber/weapon combination has to be set up to be that versatile as well. So a common lower receiver or chassis system along with multiple upper receivers/barrel lengths depending on mission and terrain might be the best way to go. Good chunk of change to do something like that when you take into account optics and everything, but the payoff in mission capabilities would be worth it in my opinion.
Overall, I'm like Koshinn. I'd like to see what our weapons are capable of without the Hague Convention requirements we place on them. But I'm also a realist in saying the normal line infantry is never going to get enough ammunition to practice at ranges from 300 to 500 meters to become proficient so the point is probably moot.
Grand58742
07-04-13, 13:57
Wrong thread lol
BrigandTwoFour
07-04-13, 14:04
The reason I brought up the 6.5G to begin with was looking at the potential for a DMR rifle as well as a carbine, like the Mk12 is to the M4. It's true the 6.5G needs a longer barrel for better ballistics (18+ inches) however, that length being not optimal for urban applications and CQB. However, seeing what the terminal ballistics are within 300-400 meters for a 14.5 or 16 inch barrel are for the 6.5 vs the 6.8 (pretty even according to your charts) but wondering how much that changes at range with a longer barrel in a 6.5G in a DMR type platform in open areas like Afghanistan. Danno said multiple uppers might be the best way of going and I think he might be on to something there. Hence, the Grendel might be a little better overall than the 6.8 especially at range.
From the Alexander Arms website, the Grendel likes a longer barrel and gets far better ballistics at range with 20 inches or more. Which tends to be close to the DMR length in current issued rifles. I'm going to assume (yeah, I'm wrong for doing so) an SBR/CQBR type setup like a Mk18 is going to give up a lot ballistically, but we aren't talking about long range shots here with that kind of weapon and the trade off of barrel length compared to accuracy might be acceptable in my opinion.
I know the conversation is about a service rifle, but the fact that the M16 FOW is and has been used from everything from SMGs up to DMR/precision setups. And any new caliber/weapon combination has to be set up to be that versatile as well. So a common lower receiver or chassis system along with multiple upper receivers/barrel lengths depending on mission and terrain might be the best way to go. Good chunk of change to do something like that when you take into account optics and everything, but the payoff in mission capabilities would be worth it in my opinion.
Overall, I'm like Koshinn. I'd like to see what our weapons are capable of without the Hague Convention requirements we place on them. But I'm also a realist in saying the normal line infantry is never going to get enough ammunition to practice at ranges from 300 to 500 meters to become proficient so the point is probably moot.
Agreed on the common lower with multiple types of uppers for different roles. A CQB upper receiver (10"-12") for close in work (and probably general issue for most people who don't have a need for anything beyond their personal defense on a FOB), general purpose receiver in the 14"-16" range for those working in the 200-300 (and perhaps more, depending on skill), and maybe a 18" for a DMR pattern.
I also agree with Doc's statement on the first page that whatever route we go should be optimized for near full burn in a 16" barrel. That may almost negate the need for anything in the 18" range as there may be too little benefit to justify the weight penalty (I'm currently struggling with this concept while planning a 6.8 SPC II upper for hunting).
I would also add attachment methods for a modular stock. Folding, adjustable precision, cheek weld, etc.
As far as cost goes, this is all just an academic exercise. But, IMO, if the DoD can afford to purchase new computers, monitors, flat screen TVs, office furniture, and many other superfluous things every year then its not a matter of not having the money. Its about budget prioritization. The government color-of-money budgeting system is broken, potentially even more broken than the bloated acquisition system.
Some units have demonstrated the value of going COTS and private development, bypassing the service acquisitions processes entirely. The development of computerized machining, 3D printing, and other rapid prototyping should lead to vastly increased concept-to-product speed. The guys coming up with alternative AR-15 receiver 3D printer files are great examples.
I think we're closer than ever to really seeing some exciting stuff happening in the small arms world.
Grand58742
07-04-13, 14:20
As far as cost goes, this is all just an academic exercise. But, IMO, if the DoD can afford to purchase new computers, monitors, flat screen TVs, office furniture, and many other superfluous things every year then its not a matter of not having the money. Its about budget prioritization. The government color-of-money budgeting system is broken, potentially even more broken than the bloated acquisition system.
I'm right there with you in knowing all about that. Not sure how much has changed from when AFSPC gave up the 20th AF to AFGSC, but when I was in AFSPC, we always had money to play around with at the end of the year. Unfortunately the USAF falls under the Army in small arms development and we follow their rules. Not exactly thinking that's the best course of action for us, but if it doesn't fly and drop bombs, the USAF doesn't care and is not willing to spend money on it. We have no small arms program so there really is no money to be wasted.
Some units have demonstrated the value of going COTS and private development, bypassing the service acquisitions processes entirely. The development of computerized machining, 3D printing, and other rapid prototyping should lead to vastly increased concept-to-product speed. The guys coming up with alternative AR-15 receiver 3D printer files are great examples.
Typically though, those units are the specialized types that can go out to different manufacturers and say "We need this doodad for this upper, can you make it work" or "We need this weapon/round and here's the money to do it." The 6.8 SPC is a prime example of special units getting assistance from the private sector in designing a unique tool for the job at hand. For the big Army (or Air Force for that matter) units don't have that luxury and end up using whatever they are issued. Sometimes it trickles down from SOF and the other special types, other times, not so much.
If you think that is what is needed, then I would say you are justified. But my original criteria was vastly better penetration and terminal effect from 0-300 and better terminal effect at 500.
Running some off the calculations on JBM....
This is a 6.5 123gr SMK running at 2750 FPS (what I would think is reasonable for the barrel lengths we're talking about)
http://img.photobucket.com/albums/v144/disposablehero/65123smk2750fps.png
This is a 6.8 135gr SMK at 2700 FPS
http://img.photobucket.com/albums/v144/disposablehero/68135smk2700fps.png
At the ranges we are realistically taking about (0-500), there is very little difference between these two. In fact, they are almost identical all the way out to 1000 yards.
But they are both vastly superior to 5.56. For reference, this is 5.56 77gr SMK at 2750
http://img.photobucket.com/albums/v144/disposablehero/77grSMK2750.png
So, coming back to an earlier point, I think either route is fine on paper here. But Doc's research shows that the 6.8 disrupts faster in soft tissue, thus causing more damage. I think the sectional density of the 6.5 was a minus in that regard. In any case, IMO, either one would be fine in a slightly larger cartridge. I think both could be loaded to the same slightly larger mag length and be run in the same rifle.
Looks like there is not that much difference between the 6.5 and 6.8 on those charts, but the velocities they are using for the 6.8spc are unrealistic. You might be able to get a 135 grain 6.8 bullet moving close to 2500fps, but there is no way it is moving a 135gr bullet at 2700fps. That bullet also cannot be loaded to magazine length.
Lighter bullets at higher velocity give you flatter trajectory and less lead on a moving target in the 0-300 range.
6.8 SPC 16" bbl - 90gr bullet @ 2850fps (bc .236)
What do x39 and 6.5 have available for high velocity loadings?
I think the answer is NONE, but I haven't looked into it.
6.5 Grendel can push a 90gr bullet over 2900fps, a 95gr at 2850 and an 85gr over 3000fps.
BrigandTwoFour
07-04-13, 16:59
Looks like there is not that much difference between the 6.5 and 6.8 on those charts, but the velocities they are using for the 6.8spc are unrealistic.
It's unrealistic for the 6.5 as well for the Grendel. Good thing we're not talking about the Grendel or SPC...
You might be able to get a 135 grain 6.8 bullet moving close to 2500fps, but there is no way it is moving a 135gr bullet at 2700fps. That bullet also cannot be loaded to magazine length.
I wasn't aware we were trying to fit a mag length yet. What magazine length are you talking about?
The 6.8 SPC is made to fit in standard M4/Ar15 magazines. From what I remember, the 135 grain load is beyond the standard dimensions for the SPC and will not fit in the standard magazine and feed reliably.
If we are talking about loading a .27 caliber round in a cartridge longer than a 6.8 SPC, then that is a whole different story. Some of us were discussing the 6.8SPC and 6.5 Grendel. What cartridge were you talking about?
BrigandTwoFour
07-04-13, 19:44
The 6.8 SPC is made to fit in standard M4/Ar15 magazines. From what I remember, the 135 grain load is beyond the standard dimensions for the SPC and will not fit in the standard magazine and feed reliably.
If we are talking about loading a .27 caliber round in a cartridge longer than a 6.8 SPC, then that is a whole different story. Some of us were discussing the 6.8SPC and 6.5 Grendel. What cartridge were you talking about?
The origin of this thread is to discuss possibilities for an entirely new service cartridge and rifle to go along with it. AR-15 magazine length is irrelevant as the "new" magazine can be whatever length we desire.
I'm not sure where you get the "some of us were discussing" part. This is NOT a thread of SPC vs Grendel and never has been. We were discussing what those cartridges bring to the AR-15 and how it could be applied to a newer intermediate cartridge.
The bolt does have to be larger for 6.5, because the bolt thrust of the larger case limits operating pressure. The problem is weight, both of rifles and ammunitions. Magazines as well.
I did not know the 6.5G uses a larger bolt. Very interesting. Do you by chance have specs on the 6.5G bolt dimensions?
Caliber conversions don't even make sense for special operations. By the time you have separate optics, conversion parts, etc you aren't saving a significant amount of money over a new rifle, and since these things will end up in the arms rooms (or an Operators conex) anyway it might as well be a whole rifle.
We can just agree to disagree on this issue.
Sorry I wasn't clear. 6.5G doesn't use a larger bolt but should. The bolt thrust is enough that they can't load the cartridge above 50k ish PSI. Now, that could be a good thing, depending on how you feel about ideal operating pressures, but it's generally considered relatively low pressure for a modern cartridge. If one was designing a 6.5G from scratch it would almost certainly have a larger bolt.
wild_wild_wes
07-04-13, 22:49
Yeah, a 6.5 round would be great, but a new metallic cartridge at this point would be the Krag all over again. At least it should be cased telescoped, if not caseless. And not just a rifle/carbine should be developed for the new ammunition, but a whole small arms family.
BoringGuy45
07-05-13, 00:37
I think how a rifle and/or cartridge is designed really comes from the base philosophy of what the actual need is. For example, in the days of the first assault rifles, we have to look at what the main players were aiming for (no pun intended). For the Germans and Soviets, the Stg.44 and AK-47 were designed essentially to be submachine guns with extra range and punch. It didn't matter that they were not pinpoint accurate and the rounds dropped like rocks at about 250-300 meters; that was better than the MP-40 and PPSh-41 did. The philosophy of their warfare was overwhelming volume.
For the Western nations, when the first assault rifles were developed, they were essentially scaled down battle rifles. The M14, FAL, G3, and later M16 and others were designed to be extremely accurate at a distance, but light enough and able to lay down enough volume of fire if the enemy closed in too close. It didn't matter that they were still heavy and cumbersome in close quarters, it still was lighter than, and carried more ammo than the bolt action rifles of WWII or even the M1 Garand.
So what are we theoretically trying to do? Are we trying to bring back the old battle rifle and make it lighter and give it more ammo, or are we trying to come up with a way to simply give the current assault rifles a little bit more punch?
I'm not sure where you get the "some of us were discussing" part. This is NOT a thread of SPC vs Grendel and never has been.
If you will read the three replies under this post of yours, you will see three other people, not including myself, who have been and still are, discussing the 6.5 Grendel. However, if you feel that we shouldn't be discussing it, I will wait until you define what this "new intermediate cartridge" that you refer to is, and then I will discuss it with everyone.
Please reply quickly as I would like to spend some time discussing SOMETHING this evening.
Grand58742
07-05-13, 18:05
If you will read the three replies under this post of yours, you will see three other people, not including myself, who have been and still are, discussing the 6.5 Grendel. However, if you feel that we shouldn't be discussing it, I will wait until you define what this "new intermediate cartridge" that you refer to is, and then I will discuss it with everyone.
Please reply quickly as I would like to spend some time discussing SOMETHING this evening.
I wouldn't say it's a 6.5 vs a 6.8 thread as both have strong attributes and some weaknesses. The 6.8 has the benefit of being far more developed by more manufacturers and having some backing from the military. The 6.5 has been shown to have superior long range performance but at the cost of increased barrel length.
But designing a new cartridge over and above existing stocks might not be a bad way to go. I wouldn't look at another metallic cartridge it as a repeat of the Krag since it eventually led to the development of the .30-06 and in turn the .308 and all calibers that spawned from those two. Metallic cartridges are still the easiest and most cost efficient method of sending a bullet downrange that exists today. And unless there is a significant breakthrough in caseless designs or at least the reliability of same, I feel we will be continuing down that path for the foreseeable future.
Overall, if this was more than a hypothetical exercise and looking for somewhat of a quick turn, it may be easier to take a round already in somewhat mass production and the civilian market has developed and matured rather than waste time an money developing a new one. The 6.8 SPC has come along far enough in development to fit this bill. I think the 6.5 Grendel has the potential to be a strong contender for the intermediate cartridge sort of role, but just hasn't been tested as extensively as the 6.8 and remains almost like a wildcat cartridge rather than a mainstream caliber. So the question would rest on whether or not the 6.5G has the same ballistic capabilities for the 0-400 meter role as the 6.8 out of the same length barrel and if major manufacturers besides Wolf and Hornady will dump money into developing it to be an all around caliber. Long range performance has been documented on both, but the 6.5 the has edge so as an intermediate DMR type cartridge, I feel it would be better suited for that role. But for the moment, the 6.8 has the benefit of development in the shorter range, shorter barrel arena so there is the answer on that. Again, it's a trade off between the two.
Back to the original question...
A modular platform with AR type ergonomics, modularity and controls, DI or piston doesn't matter (whichever is more reliable), quick swap uppers/barrels ranging from 10-18 inches with zero POI/POA change, chambered in an intermediate barrier blind caliber that performs well both in flight ballistics and terminal ballistics from 0-800 meters with maximum of 1.5 MOA in mass produced ammo and less than MOA in match grade ammo, service life of minimum of 10K rounds on high stress parts (barrels, bolts, gas system, etc), optics package depends on mission/proficiency/barrel length and a good BUIS set that can be used on ranges to 800M, minimum 1500 MRBS...and I don't want to use my non-firing hand to hit a magazine release so that excludes any H&K G36 or AK type, reliable impact resistant polymer type magazines with a lifespan of minimum of 5K rounds before failure and with zero feed lip deformation from loaded storage, around 8 lbs loaded with optic for "standard" 14.5-16 inch barrel length, removable 1913 rails with QD sling attachments in the stock and hand guards.
Not asking for a whole lot here. Just asking to take back the infantry half mile as demonstrated by the USMC in Belleau Wood. We always won't be fighting in close quarters as is being demonstrated in A-Stan.
And screw the Hague Convention...give that puppy a soft or hollow point.
The 6.5 has been shown to have superior long range performance but at the cost of increased barrel length.
Snip
So the question would rest on whether or not the 6.5G has the same ballistic capabilities for the 0-400 meter role as the 6.8 out of the same length barrel
Wondering where you are getting the "Grendel does not do as well in similar barrel lengths" info from? Don't want to rehash the dozens of debates on TOS, most by people with minimal experience with either cartridge.
I shoot Grendel extensively, not out of love for a cult cartridge, but because when I evaluate the options it offers the best combination of performance, accuracy, and reliability in the AR-15 platform. If I found 6.8 offered more, I would switch. But the accuracy & performance of both reloads and the reasonably priced Hornady ammo is just amazing, even in non-exotic rifles. For reloaders the bullet selection and downrange performance is hard to beat.
All that said, if you are designing a new rifle I'd not start with either the Grendel or 6.8.... They are excellent attempts to optimize within the AR-15 constraints, but the best route would be to deal with some of those constraints.
I'd go a bit longer cartridge length, and a bit wider magwell. Either that or go with one of the stronger bolt/barrel extension options to allow a Grendel type cartridge to be loaded to full potential. (Grendel cannot be loaded full strength in AR's due to bolt thrust limits). Either would get you 200-300 fps more, which would get you the ideal intermediate AW cartridge. We know this in Grendel as bolt gun shooters are doing that now in some of the carbines. (CZ 527 in 7.62x39 is a trivial conversion and very popular)
I am sold on 6.5mm for bore size as it is optimum BC for the 115-120gr bullet weight range. Which is a very good AW / light rifle/carbine weight. Any larger, you either lose downrange performance or get into 7.62 NATO size/recoil/cost. Any smaller and you might as well stick with 5.56.
For me this is an intellectual exercise only, as I do not believe we will see movement away from 5.56 in the next decade or two. Just too much invested, and too much organizational inertia. As such I discount any talk of military interest from either 6.8 or Grendel camps, even though I do believe them to be truthful. It's just that having interest from specific groups is a very long way from adoption or even large scale usage.
The origin of this thread is to discuss possibilities for an entirely new service cartridge and rifle to go along with it. AR-15 magazine length is irrelevant as the "new" magazine can be whatever length we desire.
To an extent.
Handiness of manipulation is an important factor to consider.
I think everyone agrees that AR15 mags are very easy to grasp and manipulate.
I'm mid sized and find the AR10/308 sized mags notably harder to control, mostly due to the length.
IMO, any increased length cartridge should stay under 2.4-2.5"
The new Magpul 6.8 Pmags allow 2.320" COL
Sorry I wasn't clear. 6.5G doesn't use a larger bolt but should. The bolt thrust is enough that they can't load the cartridge above 50k ish PSI. Now, that could be a good thing, depending on how you feel about ideal operating pressures, but it's generally considered relatively low pressure for a modern cartridge. If one was designing a 6.5G from scratch it would almost certainly have a larger bolt.
I believe the new 6.8 90grain is only loaded to 52k, most likely for reliability reasons.
5.56 - .378" rim
6.8 - .422" rim
6.5 - .440" rim
7.62 - .473" rim
I agree that a medium sized bolt with improved geometry should be used that is optimized for .420-.440" size rims.
The bolt should allow 65k pressures to accommodate any specialty heavy long range loads, while standard loads can remain <55k for good functional reliability in full auto fire at 130F ambient.
Grand58742
07-06-13, 15:27
Wondering where you are getting the "Grendel does not do as well in similar barrel lengths" info from? Don't want to rehash the dozens of debates on TOS, most by people with minimal experience with either cartridge.
If you noticed, I posed the question rather than make a qualified (which I'm not able to do) judgment on either cartridge and instead read as much as I can about both. And from all accounts, the 6.5 is dependent on longer barrel lengths for better performance.
The Grendel charts from Alexander Arms:
http://www.alexanderarms.com/images/pdfs/grendel_ballistics.pdf
Shows a significant decrease in velocity from a 19.5 inch barrel to a 14.5 inch barrel. And nothing listed under the 14.5 inch barrel.
And per the AA website:
This mainly refers to the 6.5 Grendel as the .50 Beowulf® is best in a 16" barrel. The two 6.5 Grendel barrels that are best suited for hunting are the 24" and 20" barrels. The shorter tactical barrels may be applied, but, beyond slightly lighter weight and handier silhouette, they have no advantage and give up velocity. However, they are superb choices for general shooting or a utility rifle. The 24" 6.5 Grendel is well-suited to most hunting applications and, if one can live with the longer barrel, it is the most versatile of the 6.5 Grendel barrels. Accuracy is superb and the rifle is capable out to 1,000 yards with the right ammunition. The balance of the gun assists stability in most position-shooting and it is excellent for use from a bipod. This one barrel can bridge across a range of shooting tasks including long-range varmint work. The 20" barrel 6.5 Grendel is both shorter and lighter than the 24" gun, which is a big consideration if the gun must be carried. While it gives up some stability from a bipod, it is just a versatile.
Bold emphasis added by me. Which does support the longer barrel claim. However, a 24 inch barrel is not exactly the ideal length in today's combat environment and the numbers show the 16-19.5 inch as being suited for an all around barrel length.
As for the 6.8 barrel lengths:
https://www.m4carbine.net/showpost.php?p=1084322&postcount=6
and the very last paragraph here:
https://www.m4carbine.net/showthread.php?t=19878
Which does bring back the question I asked of the side by side comparison of the 6.8 vs the 6.5 out of similar barrel lengths as well as terminal ballistics. I know Doc has extensively tested the 6.8 and is a proponent. Not sure about the 6.5 testing but I might assume he has done some at some point. I know Alex Arms has some pictures of some gel tests done on their website under the ammo heading, but no accompanying data save the velocity and penetration numbers.
So we come back to the original point. Does the 6.5G have the same ballistic capabilities out of the same length barrel as the 6.8 at the same ranges? Not intended to argue one over the other, I'm genuinely curious.
Unfortunately, the 6.5G just hasn't been developed as much as other calibers and remains for the most part a niche cartridge where the best performance is achieved through hand loading. I would like to see more manufacturers get on board and wring as much potential out of the cartridge as possible.
wild_wild_wes
07-06-13, 17:54
...if you are designing a new rifle I'd not start with either the Grendel or 6.8.... They are excellent attempts to optimize within the AR-15 constraints, but the best route would be to deal with some of those constraints...I'd go a bit longer cartridge length...I am sold on 6.5mm for bore size as it is optimum BC for the 115-120gr bullet weight range. Which is a very good AW / light rifle/carbine weight. Any larger, you either lose downrange performance or get into 7.62 NATO size/recoil/cost. Any smaller and you might as well stick with 5.56.
If we were just talking only using one of those cartridges as is, I think the Grendel would be the better choice, as it would allow for longer-range use out of LMGs as well as an assault rifle.
But if we were looking at a whole small arms cartridge family, neither would be optimal. In that case a more powerful 6.5 with longer case would rock, for use by both LMGs and DMs. And as was already said, a shorter case 5.56 would fill the need for most small arms users, in the form of a PDW.
There's the 260 Remington and 6.5 Creedmoor. They are great cartridges, but you are creeping back up into .308 Rem territory as fas as size and weight of the cases.
There is also the .270-08 (6.8) wildcat. I would like to see a side by side ballistic comparison of that and the 260 Remington, since they are both based on the same 308 winchester case.
I think stepping down one half millimeter (6mm PPC/243 winchester), is going too far in the direction of the .223.
Stepping up one millimeter (7mm-08) is getting too close to the .308 in terms of size recoil and weight.
Something hovering around 6.5 or 6.8 seems to be magic in terms of low recoil and great ballistic coefficients.
What if somebody lengthened the 6.5G to the limit of the UCIW magwell?
As somebody already mentioned the Magpul 6.8 PMag which is designed for the UCIW magwell and won't fit in a normal AR lower.
If we were just talking only using one of those cartridges as is, I think the Grendel would be the better choice, as it would allow for longer-range use out of LMGs as well as an assault rifle.
But if we were looking at a whole small arms cartridge family, neither would be optimal. In that case a more powerful 6.5 with longer case would rock, for use by both LMGs and DMs. And as was already said, a shorter case 5.56 would fill the need for most small arms users, in the form of a PDW.
The last thing we need is to feed the same cartridges into a rifle and machine gun. Ask a logistician if you can interchange ammo from an M4 to a SAW or vice versa. Aside from the mag feed system that causes trouble, you can't. Different items for linked and unlinked ammo. Furthermore you'll want different ammunition. The DMR should fire special ball with potential for groups in the range of 1 minute or .3mil. The machine gun might as well fire copper washed steel to save money and increase penetration. The accuracy of the weapon need only allow for a 2 mil beaten zone. You'll also want a bullet suited for penetration.
The original SAW should have been in 6mm SAW or at least used 5.56 with an 80 grain bullet loaded to 2.55".
Surprised no one's mentioned the .280 Brit developed in the '50s. Might not be having this discussion if it had been adopted by NATO instead of the 7,62x51.
I don't even get the "Grendel does better out of longer barrels" argument. Everything does!
If the Grendel is going faster to begin with, and has better ballistic coefficients than the 6.8 or 7.62x39 in a 24 inch barrel, it will still be going faster and have better ballistic coefficients if they are all in a 14 inch barrel.
I don't know of any rifle bullet that gets faster in a shorter barrel. Please explain how ONLY the Grendel is hampered by being in shorter barrels...
Surprised no one's mentioned the .280 Brit developed in the '50s. Might not be having this discussion if it had been adopted by NATO instead of the 7,62x51.
I personally think it would have been great if the NATO had adopted the 6.5x55 Swedish Mauser, or even the 7x57 Mauser instead of the 7.62x51. They would then have had the 60 years worth of development the 7.62 has seen. We would have tons of rifles with better ballistic coefficients and less recoil for sporting use.
SomeOtherGuy
07-08-13, 09:12
I don't know of any rifle bullet that gets faster in a shorter barrel. Please explain how ONLY the Grendel is hampered by being in shorter barrels...
Grendel fans don't like seeing their cartridge lobbing bullets at 300BLK velocities despite requiring special, weak bolts and special magazines. That's about it. (Yes, of course, 6.5G will lob a better BC bullet at a given velocity than 300BLK, but for many loads you're still looking at rainbow trajectories. Remember, .45-70 will make it out to a kilometer easily, just not with a little 8 mil elevation adjustment.)
SomeOtherGuy
07-08-13, 09:20
Keeping the 5.56 case dimensions but enlarging to a 6 or 6.5mm bullet would provide an incremental increase in barrier penetration, wounding, retained energy at long range (due to higher BC), and relative performance in short barrels (due to higher expansion ratio), all while allowing continued use of everything except barrels. If there was a need for a right-away improvement, this would provide it, just nothing spectacular. It would also cause only a slight increase in ammunition weight, which would be very important to the infantry.
6.8 SPC provides more & better for all those good things, but requires bolts, magazines and barrels to be changed (and belt links for belt-fed weapons). It also causes a greater weight increase, especially if you want the more effective 110-120gr bullets. It could be a good option too.
Anything bigger or heavier than 6.8 SPC probably makes the ammo standard load too heavy, and may make the rifle bigger and heavier too, for ordinary infantry or PDW type use.
Grendel fans don't like seeing their cartridge lobbing bullets at 300BLK velocities despite requiring special, weak bolts and special magazines. That's about it. (Yes, of course, 6.5G will lob a better BC bullet at a given velocity than 300BLK, but for many loads you're still looking at rainbow trajectories. Remember, .45-70 will make it out to a kilometer easily, just not with a little 8 mil elevation adjustment.)
I know you were trying to be "smart", but it's not working very well...
1) Grendel requires a stronger bolt, not weaker for a given case pressure. As does any other cartridge which increases head diameter including 6.8, the .4xx's whatever. This is due to the physics, as the case PSI acts on a larger surface area, and creates more bolt thrust.
2) Just opening up the face of a bolt does weaken it for given steel strength. Current mfg's can get away with doing that for 7.62x39 as the pressure is low enough to get by. But they still break. Steel improvements have allowed LMT and similar to improve this, but they are still weaker.
Alexander went back to Colt's original 7.62x39 design, which was required due to weaker steels back then. It addresses the strength issue by moving the stress points deeper in the bolt. Too complicated to explain here, but the Colt 7.62x39/Grendel bolt is stronger even though it's machined deeper, when measured using the same steels. (Stronger meaning it will handle higher case pressure)
With the combined use of Colt's bolt approach and modern steels, Grendel bolts have reached parity with 5.56 reliability standards, even when producing way more energy.
3) Let's talk trajectories. If you want to lob watermelons, 300BLK is for you. If you want to shoot 55g pills, then .223 works great. Grendel & SPC were designed to close that gap to find a happy medium.
And specifically, Grendel was designed to optimize 115-125g down range performance in an AR-15 Platform. For some very specific reasons, and by some very specific measures.
All the talk dismissing BC's demonstrates ignorance. Check the velocities and retained energy downrange. That's one piece. Then see which are still supersonic. It's key... as bullets destabilize when transitioned out of supersonic flight. Much more to the puzzle!
Otherwise we'd all just stuff 6.5mm (or 6.8) bullets in one of the dozen 5.56 based hybrids and be done. But they don't stay supersonic down range far enough to be useful!
Watermelons are different. The magic of the whisper was you start and stay subsonic. And use big bullets with decent BC's for their size to remain stable. (I want to say it was sectional density that also mattered). But definitely a different stability approach.
It's all an optimization game. 6.5 Optimum BC's are in the 115-125g range. 6.8/270 closer to 130. 7mm 140-150. 7.62 165 or so. Higher if you go sub-sonic.
But you have to fit in a "package", in Grendel/SPC case, the AR magwell , bolt, & barrel extension constraints. So that pushes you back into the low 100g range for optimal down range perfomance. Very hard to fit the long bullets into the AR-15 magwell and keep case capacity.
Then you start dealing with barrel lengths. All cartridges improve performance with increased barrel lengths. It's physics. And as barrels shorten, you have to change powder characteristics to optimize muzzel vel and recoil. (Yes, there is a recoil difference just due to the weight of the powder, as it's mass that has to be accelerated even if as gas)
But you also have to factor in typical/target barrel lengths for your format. There are some optimum bullet weights for each barrel length if you are trying to maximize downrange performance. 16-18" seems to be standard, with carbines/CQB shorter. 20" (from feedback) too long for most now due to vehicle and CQB usage.
Going shorter you reach a point where very heavy bullets can work better in very short barrels with typical powders. Could you optimize Grendel/6.8 for pistol length? Yes, but thats not at all what it was designed for. Would it beat 300? Probably not.
If you jump to 7.62 NATO sized formats and capabilities, it's already pretty optimum. Yes, you could drop to 260 or similar and improve downrange performance. But it's nominal improvement and only at longer ranges. And you now are back to Battle rifle recoil levels, ammo capacity/weight constraints, etc.
Grendel was optimized for downrange performance in typical AR-15/AK platforms. No more no less. And that's pretty interesting for some of us.
It's not magic, just a reasonable sweet spot for the platforms. I'd view 6.8 a close second for my interests with the current loadings. But I'd give up some flexibility that are important to me. Like being able to reload 7.62x39 brass into grendel, or to have steel case grendel made on russian lines with minimal tooling changes.
And I really like the 6.5mm bullet selection for combined home defense / hunting / paper punching role. FMJ requirements change all that, not as many good FMJ options, but some of the target bullets might could pass the test.
But were I starting fresh to design an optimal infantry carbine/rifle, I'd go a hair bigger on magwell length than the AR-15. Bigger barrel extension/bolt to allow bolt gun pressures. Probably take grendel or SPC and grow it just a bit in length. Widen the mag a bit to allow standard stacking (each cartridge touches two others) with poly magazines. (SPC and grendel only stack right in steel mags due to space constraints)
I am convinced that 115-125 is a very versatile bullet weight for typical infantry barrel lengths. So I'd probably stick with that. Which means to me that 6.5mm is the sweet spot for our new cartridge, all other things being equal.
Keeping the 5.56 case dimensions but enlarging to a 6 or 6.5mm bullet would provide an incremental increase in barrier penetration, wounding, retained energy at long range (due to higher BC), and relative performance in short barrels (due to higher expansion ratio), all while allowing continued use of everything except barrels.
Just not enough steam downrange to keep them supersonic, people keep forgetting that. (at least at the longer ranges we are trying to address)
And probably not enough improvement to justify the millions it would cost, even if less than totally new platform.
Trust me, many folks have explored this path, myself included. There are viable 5.56 based 6 & 6.5mm variants out there. Fun for plinking. Less useful for hunting and combat.
Just to go old school, how about the 139 gr 7x57 Mauser. Or to get in the 100 to 120 gr range, how about the .257 Roberts?
http://www.chuckhawks.com/recoil_table.htm
SomeOtherGuy
07-08-13, 14:37
You've just proven my and Greenlion's points - both about 6.5 Grendel, and about its fan club.
1-2) Yes, I'm well aware that Grendel needs more bolt strength due to thrust resulting from the larger case head area. I'm also aware that the AR15 bolt is on the edge to begin with, and cutting away material while applying more force isn't going to end well. 6.8 SPC has its funky case head size because its designers were trying to balance this issue. To really fix it you just need a different bolt design.
3) No, I'm not ignorant of the importance of BC's. Instead, I am aware that 6.5 Grendel in real-world length barrels produces ballistics that are not exceptional. The really good Grendel numbers come from 24" barrels. 5.56 also produces impressive numbers in 24" barrels, except no one actually uses them for military purposes.
I know you were trying to be "smart", but it's not working very well...
1) Grendel requires a stronger bolt, not weaker for a given case pressure. As does any other cartridge which increases head diameter including 6.8, the .4xx's whatever. This is due to the physics, as the case PSI acts on a larger surface area, and creates more bolt thrust.
2) Just opening up the face of a bolt does weaken it for given steel strength. Current mfg's can get away with doing that for 7.62x39 as the pressure is low enough to get by. But they still break. Steel improvements have allowed LMT and similar to improve this, but they are still weaker.
Alexander went back to Colt's original 7.62x39 design, which was required due to weaker steels back then. It addresses the strength issue by moving the stress points deeper in the bolt. Too complicated to explain here, but the Colt 7.62x39/Grendel bolt is stronger even though it's machined deeper, when measured using the same steels. (Stronger meaning it will handle higher case pressure)
With the combined use of Colt's bolt approach and modern steels, Grendel bolts have reached parity with 5.56 reliability standards, even when producing way more energy.
3) Let's talk trajectories. If you want to lob watermelons, 300BLK is for you. If you want to shoot 55g pills, then .223 works great. Grendel & SPC were designed to close that gap to find a happy medium.
And specifically, Grendel was designed to optimize 115-125g down range performance in an AR-15 Platform. For some very specific reasons, and by some very specific measures.
All the talk dismissing BC's demonstrates ignorance. Check the velocities and retained energy downrange. That's one piece. Then see which are still supersonic. It's key... as bullets destabilize when transitioned out of supersonic flight. Much more to the puzzle!
Otherwise we'd all just stuff 6.5mm (or 6.8) bullets in one of the dozen 5.56 based hybrids and be done. But they don't stay supersonic down range far enough to be useful!
Watermelons are different. The magic of the whisper was you start and stay subsonic. And use big bullets with decent BC's for their size to remain stable. (I want to say it was sectional density that also mattered). But definitely a different stability approach.
It's all an optimization game. 6.5 Optimum BC's are in the 115-125g range. 6.8/270 closer to 130. 7mm 140-150. 7.62 165 or so. Higher if you go sub-sonic.
But you have to fit in a "package", in Grendel/SPC case, the AR magwell , bolt, & barrel extension constraints. So that pushes you back into the low 100g range for optimal down range perfomance. Very hard to fit the long bullets into the AR-15 magwell and keep case capacity.
Then you start dealing with barrel lengths. All cartridges improve performance with increased barrel lengths. It's physics. And as barrels shorten, you have to change powder characteristics to optimize muzzel vel and recoil. (Yes, there is a recoil difference just due to the weight of the powder, as it's mass that has to be accelerated even if as gas)
But you also have to factor in typical/target barrel lengths for your format. There are some optimum bullet weights for each barrel length if you are trying to maximize downrange performance. 16-18" seems to be standard, with carbines/CQB shorter. 20" (from feedback) too long for most now due to vehicle and CQB usage.
Going shorter you reach a point where very heavy bullets can work better in very short barrels with typical powders. Could you optimize Grendel/6.8 for pistol length? Yes, but thats not at all what it was designed for. Would it beat 300? Probably not.
If you jump to 7.62 NATO sized formats and capabilities, it's already pretty optimum. Yes, you could drop to 260 or similar and improve downrange performance. But it's nominal improvement and only at longer ranges. And you now are back to Battle rifle recoil levels, ammo capacity/weight constraints, etc.
Grendel was optimized for downrange performance in typical AR-15/AK platforms. No more no less. And that's pretty interesting for some of us.
It's not magic, just a reasonable sweet spot for the platforms. I'd view 6.8 a close second for my interests with the current loadings. But I'd give up some flexibility that are important to me. Like being able to reload 7.62x39 brass into grendel, or to have steel case grendel made on russian lines with minimal tooling changes.
And I really like the 6.5mm bullet selection for combined home defense / hunting / paper punching role. FMJ requirements change all that, not as many good FMJ options, but some of the target bullets might could pass the test.
But were I starting fresh to design an optimal infantry carbine/rifle, I'd go a hair bigger on magwell length than the AR-15. Bigger barrel extension/bolt to allow bolt gun pressures. Probably take grendel or SPC and grow it just a bit in length. Widen the mag a bit to allow standard stacking (each cartridge touches two others) with poly magazines. (SPC and grendel only stack right in steel mags due to space constraints)
I am convinced that 115-125 is a very versatile bullet weight for typical infantry barrel lengths. So I'd probably stick with that. Which means to me that 6.5mm is the sweet spot for our new cartridge, all other things being equal.
Any thoughts on the 6.5x47 Lapua, other than the fact it is rather pricey?
BrigandTwoFour
07-08-13, 21:15
Any thoughts on the 6.5x47 Lapua, other than the fact it is rather pricey?
By all accounts I've read, it's a good caliber for long range. In the same class with .260 and 6.5 Creedmoor with a bit more power. But, IMO, it's too much for an intermediate assault rifle caliber. I wouldn't be too concerned with "pricey," though. If a caliber gets adopted as standard issue, economy of scale would bring the prices down significantly.
The thing that interests me about the 6.5 vs 6.8 caliber cartridges is the terminal effect at varying velocities. It's certainly true that the the 6.5's better BC will catch up to and surpass many other bullets, and that's a great feature when comparing the two punching paper and range. But what is the velocity threshold for fragmentation, tumbling, and other serious terminal effects? If the 6.5 requires higher velocities to generate the same terminal effect as a 6.8 at lower velocities, then shorter barreled rifles clearly favor the 6.8
But I don't have the facts to back this up. All I have is the tests that Doc posted int he 7mm Murray thread saying that the 6.5 did not cause as much tissue damage when compared to 6.8 or 7mm bullets.
By all accounts I've read, it's a good caliber for long range. In the same class with .260 and 6.5 Creedmoor with a bit more power.
Smaller case with small rifle primers and higher pressure. It's not a great choice for autoloaders and is meant for 120-130gr bullets. It was developed for 300m competition.
6.5LR or 6.5 Creedmoor would be better choices, but still, that is the same size and weight as 7.62.
I don't even get the "Grendel does better out of longer barrels" argument. Everything does!
If the Grendel is going faster to begin with, and has better ballistic coefficients than the 6.8 or 7.62x39 in a 24 inch barrel, it will still be going faster and have better ballistic coefficients if they are all in a 14 inch barrel.
I don't know of any rifle bullet that gets faster in a shorter barrel. Please explain how ONLY the Grendel is hampered by being in shorter barrels...
Some calibers suffer more than others in short barrels. 6.5 is one of them.
Where's that one kid who started a thread about a .338 PDW? This thread would be right up his alley :p
BoringGuy45
07-08-13, 22:37
In a hypothetical rifle, perhaps even with an AR design, maybe it would be possible to redesign or enlarge the bolt head so that the same relative thickness is kept for larger cases.
My idea of a good service rifle.
1) 6mm cartridge based on the .223 case
2) 100g bullet to buck the wind well out to 600 yards
3) Lower sight plane than the M-16
4) Ambidextrous safety
5) Side charging handle that can be easily moved to the other side of the rifle for left handed shooters
6) Gas system similar to the AK-47 that will reliably operate with 10" to 20" barrels
7) Barrel that can be easily replaced at the field depot level
8) 5 lb. trigger pull
9) Under 10 lbs. with loaded magazine, sling and cleaning kit
10) 100% American made
You've just proven my and Greenlion's points - both about 6.5 Grendel, and about its fan club.
3) No, I'm not ignorant of the importance of BC's. Instead, I am aware that 6.5 Grendel in real-world length barrels produces ballistics that are not exceptional. The really good Grendel numbers come from 24" barrels. 5.56 also produces impressive numbers in 24" barrels, except no one actually uses them for military purposes.
So school me, what are you proposing/recommending?
My comment was that 6.5 (Grendelish) at full power (remove bolt/barrel ext constraint) would have the increased power of the 6.8 and the improved downrange performance of grendel. You could add a bit more capacity to either and improve the story without getting into weight/recoil problems.
But the idea that Grendel does not work out of 16" barrels is just silly. Compare grendel/6.8/6.8-II/300AAC side by side out of 16" barrels.
The hottest 6.8-II is a bit hotter at the muzzle (energy), but they are all roughly tied at 100 yards, and Grendel beats them all by 200 yards. By 400, no contest, whether measured by energy, drop, time to target, etc.
But they are so close it's more an (never ending) debate as to whether 50 yard or 200 yard performance is more critical. (As they are virtually tied at 100). And depending on the war you pick, you could make the case either way. Add in wind drift, ttt, drop, and some less visible differences surface. But they are still very close.
Were I the army, I'd give the edge to SPC-II, as so many more of the engagements are shorter than 100 yards. And I don't think the training is there to really support 200-500 yard routine marksmanship enough to utilize any advantage Grendel has. But I'm not the Army, I wanted something that performed well 100-300 and was hunting capable.
I do agree that the 6.8 has been developed a bit more. Early on, even at the closer ranges grendel had more of an edge as 6.8-II was not around, and the 6.8 projectiles were not well optimized.
Now that there are some very nice 6.8 BC's in 110-120 range 6.8-II and SSA tactical loadings are an attractive option.
If you want to talk 9" barrels and PDW role, then clearly 300 AAC becomes dominant. grendel & SPC could be optimized a bit with different powder choices, but for pistol length it's hard to beat big, slower pills.
But this is not a Grendel vs whatever discussion.
Remove the pressure constraint on the bolt for the new rifle, and even Grendel with no other changes moves past the hottest 6.8's at the muzzle, and the story just improves from there. Can't dial 6.8-II up much more, it's already nearing max pressure.
Which makes me conclude that 6.5mm 115-125 gr projectiles in a grendel+ (slightly longer) case may well be optimum in AR'ish/AK'ish carbine platforms when you factor in recoil, overall length, projectile performance, etc. BC's matter!
You can design your own optimal cartridge, but that would be mine!
SomeOtherGuy
07-08-13, 23:44
So school me, what are you proposing/recommending?
***
Which makes me conclude that 6.5mm 115-125 gr projectiles in a grendel+ (slightly longer) case may well be optimum in AR'ish/AK'ish carbine platforms when you factor in recoil, overall length, projectile performance, etc. BC's matter!
You can design your own optimal cartridge, but that would be mine!
I'm basically proposing that for all its defects, the 5.56 is not an awful compromise for how an average soldier (not SF) uses a carbine/rifle. I think it mostly suffers from the tiny, low-BC bullet and severe loss of velocity and effectiveness in short barrels. I think this could be partially remedied by going to a 6mm or 6.5mm bullet in the 5.56 pattern case, without swinging too far towards an excessively heavy ammo load, excess recoil, or needing a whole new platform to accommodate a longer or wider case. These cartridges wouldn't be as powerful as 6.5G or 6.8 SPC, but they wouldn't require as many parts to be replaced, or as much additional weight of ammo.
If I were equipping SF units for desert/mountain type operations, or willing to have DMRs in a squad using a different cartridge than everyone else, I would be looking at a larger platform with something like a .260 Rem or 6.5 Creedmore, providing a high-BC, long range cartridge with slightly less recoil and ammunition weight than .308. Or maybe that sort of thing in 6.8mm, since that was apparently the best compromise bullet size for military purposes with shorter cases. Or just use .308, which is entirely decent. All cartridges are compromises.
I'm basically proposing that for all its defects, the 5.56 is not an awful compromise for how an average soldier (not SF) uses a carbine/rifle.
Snip
And about SF type roles:
Or just use .308, which is entirely decent. All cartridges are compromises.
Then you and I are basically at the same place... realistically, I don't see a case for the Army to change from the current 5.56/.308 reality.
If we were starting from scratch I'd probably rethink caliber a bit, but for all but the last Afghan experience 5.56 seems to have done OK. And I'm not sure the modern army reduced training protocol would support anything more advanced or demanding.
3) Lower sight plane than the M-16
Bad. You then have to use a riser to be able to use iron sights and a scope on the same rifle. You also can't put lasers and such on the top rail.
The thing that interests me about the 6.5 vs 6.8 caliber cartridges is the terminal effect at varying velocities. It's certainly true that the the 6.5's better BC will catch up to and surpass many other bullets, and that's a great feature when comparing the two punching paper and range. But what is the velocity threshold for fragmentation, tumbling, and other serious terminal effects? If the 6.5 requires higher velocities to generate the same terminal effect as a 6.8 at lower velocities, then shorter barreled rifles clearly favor the 6.8
But I don't have the facts to back this up. All I have is the tests that Doc posted int he 7mm Murray thread saying that the 6.5 did not cause as much tissue damage when compared to 6.8 or 7mm bullets.
Most projectiles have a minimum expansion / fragmentation velocity.
This, combined with muzzle velocity and BC produce a "maximum performance range", which is sometimes called "frag range" in 5.56 circles.
Maximum performance range is the max range at which adequate expansion / fragmentation will occur. This expansion is an important factor for good terminal effect.
Generally speaking, Bigger expanded diameter is better, provided penetration is adequate.
Immediate incapacitation is most important at close ranges, where threats are highest. Good CNS hits within the MPR should produce it.
Many common 6.8 projectiles have a Minimum expansion velocity of 1900 fps.
Several have limits in the 1600-1700 fps.
The MPR for 6.8 loads from a 16" barrel ranges between 250-400 yards. The new XM68GD is ~400 yards.
The MPR for 6.8 loads from a 8.5" barrel ranges between 100-250 yards. The new XM68GD is ~250 yards.
Actually, most of the bullets used in the 6.5 Grendel have only average BCs because it's limited by overall length. Those used in the 6.8 are worse. The cases for both are fat, making for a wider, longer magazine.
Necking the 5.56 up to 6mm or 6.5mm puts us right back where we started with the Grendel and SPC- using stubby bullets because we're limited by overall length. It will also reduce velocity.
The problem with this conversation is that the thinking is limited by the AR experience. Cartridge ideas keep following the convoluted paths that lead to the Grendel and SPC in the first place- trying to get a bigger bullet to fit within the limits of the AR magazine.
First, realize the 5.56 isn't a bad cartridge. It's just limited by having to fit the AR. Starting with a new rifle eliminates that restriction.
First, necking up the 5.56 case to take a 6mm or 6.5 bullet means the bullet must be even longer to get good BC numbers. The larger the diameter, the longer the bullet needs to be to lower the drag.
So instead of necking the 5.56 up, why not just lengthen the bullet? Why not go with an 80, 90 or 100 gr VLD (Very Low Drag) bullet design to get the BC up really high with minimal loss of velocity? In fact, the case could be lengthened a bit to increase capacity and get velocities back up. VLD bullets also have the advantage of being unstable when transitioning mediums- going from travelling through to travelling through soft tissue- improving "tumbling". You would have the advantage of starting with a higher muzzle velocity, retention of that velocity down range and increased tissue destruction on impact with minimal increase in recoil and weight. It would also improve the performance of 5.56 DMR and SAW type weapons. The other advantage is that magazines don't have to be made thicker or longer to get the same capacity. They just have to accommodate the longer OAL of the new cartridge
In fact, it's always amazed me that they developed a completely new cartridge, the 223/5.56 instead of starting with the already established 222 Remington Magnum in the first place.
Going with a VLD bullet in a 5.56 case is probably the best bang for the buck solution
BrigandTwoFour
07-09-13, 08:46
The problem with this conversation is that the thinking is limited by the AR experience. Cartridge ideas keep following the convoluted paths that lead to the Grendel and SPC in the first place- trying to get a bigger bullet to fit within the limits of the AR magazine.
This is what I keep thinking. The thread is about thinking of an entirely new cartridge and rifle that is unhampered by the AR-15 dimensions, but I keep seeing people try and work with AR-15 mag length.
Also, some keep thinking along the lines of could/should we field a new caliber and rifle. I realize that the possibility of this discussion actually leading to a change is pretty much non-existant. But the question isn't if we could or should field a new cartridge for the military. I wanted to see what the users of M4C, based upon history, experience, and amassed technical know-how, think an ideal infantry combat cartridge and rifle would look like.
Bad. You then have to use a riser to be able to use iron sights and a scope on the same rifle. You also can't put lasers and such on the top rail.
I have given a lot of thought about lower sight plane versus the AR sight plane for years. In my opinion the front sight base is too high, which is why a lot of people are cutting their FSB down or installing a flat gas block on their rifles.
I have had to address issues related to canting the rifle with people I have trained since 1985. It is an issue for engaging targets at 250 yards and beyond. That lead me to suggest # 3.
In order to effectively lower the sight plane of the AR, the comb must be lowered. To do that, the receiver extension must be redesigned.
The advantage of the lowered sight plane is that it raises the bore in relationship to the eye, reducing the profile of the shooter's head when shooting from cover. The disadvantage is that recoil is no longer inline with the bore from muzzle to butt, increasing muzzle displacement
Requirements:
optimal 7lbs, thresh 7.5lbs
optimal 1moa, thresh 1.75moa
optimal 20% increase in ammunition weight, thresh 50%
High BC, high lethality long distance projectile, effective to 800m
Change-able LOP, and grip size (distance to trigger/safety) to accommodate 90% military aged males.
Suggestions
-two modular upper solution, IVO, 12" & 16".
-DI for longer version and a piston for shorter.
-Trigger finger bolt release ala Rem ACR other manner
-inline recoil ala AR
The thing that interests me about the 6.5 vs 6.8 caliber cartridges is the terminal effect at varying velocities. It's certainly true that the the 6.5's better BC will catch up to and surpass many other bullets, and that's a great feature when comparing the two punching paper and range. But what is the velocity threshold for fragmentation, tumbling, and other serious terminal effects? If the 6.5 requires higher velocities to generate the same terminal effect as a 6.8 at lower velocities, then shorter barreled rifles clearly favor the 6.8
But I don't have the facts to back this up. All I have is the tests that Doc posted int he 7mm Murray thread saying that the 6.5 did not cause as much tissue damage when compared to 6.8 or 7mm bullets.
The difference between 6.5 and 6.8 area is so small that bullet design and velocity dominate the performance.
I'd have to go back and look at Doc's testing to see which projectile was used. But you reach a point that the retained velocity/energy definitely overrides that nominal cross-section advantage for bullets with equal construction. From memory this was far enough back that he did not have any of the current grendel optimized projectiles.
All of the AR medium bore cartridges need projectiles which expand at the lower velocities found at range. IE: projectiles which were great in Creedmore, 6.5x57, etc may be too thickly jacketed for the AR cartridges/constraints. Same for length, ogive, etc.
Hornady has done a great job with 6.5/6.8 projectiles to get decent BC while keeping the ogive to something that works with the mag length restrictions and avoiding too deep seating. Then they took the excellent 123 AMAX and made an SST hunting bullet that kept the BC and exact length. We interchange them as needed.
I do think SPC has more development in the FMJ / military projectile space, that is a recognized gap for Grendel. It's more of a fragmentation thing than a ballistics issue.
But for hunting, there are many good options now for both grendel and SPC that work at range. But that does not help the military need, just underscores that bullets can be optimized for the intended need.
With the lower velocities of supersonic 300 AAC it's even more of an issue at range.
This is not a new issue, Sierra and others made special 7mm projectiles in the 80's for hunting with 7BR, etc as the bullets optimized for 20-24" did not do well out of 12-16" hunting pistols.
I'd have to find it, but Hornady shared the minimum expansion velocities for several 6.5 projectiles including the ones optimized for Grendel. Clearly shows the difference.
- Barrels removable/replaceable with simple tools at armorer level. I'm on the fence re: QC. Steyr got it right 35 years ago with the AUG. if this can be adapted to a new system, it would work well I feel. But a non-QC barrel would simplify (and lessen costs) the system.
Do you mean a removable barrel similar to the FN SCAR or Tavor?
My idea of a good service rifle.
5) Side charging handle that can be easily moved to the other side of the rifle for left handed shooters
The AR has this. The Raptor charging handle in particular is awesome. Many upsides to it and it's placement. Downsides are it leaks gas into your eyes and you can't use a riser on the stock unless it's carefully designed to work around this issue. On the whole I would not relocate the charging handle.
I have given a lot of thought about lower sight plane versus the AR sight plane for years. In my opinion the front sight base is too high, which is why a lot of people are cutting their FSB down or installing a flat gas block on their rifles.
I have had to address issues related to canting the rifle with people I have trained since 1985. It is an issue for engaging targets at 250 yards and beyond. That lead me to suggest # 3.
Canting is always an issue, even with low sights. I shoot fairly effectively on mini-poppers out to 100m with the rifle held parallel to the ground (SBU prone) so it can be accounted for, or you can learn to not cant it.
People cut down their sights or use folding sights because they don't want to interfere with their optics--period, full stop. On a rifle with a low sight height over bore, your iron sights and optics are on a separate plane and require, if you are to have both available without tools, a riser that can be lowered or removed. They also make cowitness impossible, a thumb over grip blocks the sights, and you can't mount night fighting equipment on the front of the rifle for easy switching because it blocks the sights. I'll pass.
Nothing wrong with the M16. If Stoner had chambered it in .243 in the beginning everything would be fine.
Grand58742
07-09-13, 16:54
This is what I keep thinking. The thread is about thinking of an entirely new cartridge and rifle that is unhampered by the AR-15 dimensions, but I keep seeing people try and work with AR-15 mag length.
I that's because the AR magazine is very user friendly, carries a good amount of rounds for it's size and, with modern polymer designs, are reasonably sturdy for everything from arctic conditions to the moon dust in Afghanistan. It's one of those things they pretty much got right with the design from the start and when combined with the ergonomics of the M16 FOW make an unbeatable pair. And it's really hard to improve on the basic overall design which is why with the exception of the G36 and XM8 nobody has really tried to design anything else in a 5.56 package.
Guess we're trying to shoehorn a new system into an old magazine. Overall, the AR mag could be modified to be a bit bigger (like the LWRC 6.8 mags) to accommodate a slightly larger round, say between the 5.56 and 7.62 types. But overall, I personally say go with that same pattern.
So instead of necking the 5.56 up, why not just lengthen the bullet? Why not go with an 80, 90 or 100 gr VLD (Very Low Drag) bullet design to get the BC up really high with minimal loss of velocity? In fact, the case could be lengthened a bit to increase capacity and get velocities back up. VLD bullets also have the advantage of being unstable when transitioning mediums- going from travelling through to travelling through soft tissue- improving "tumbling". You would have the advantage of starting with a higher muzzle velocity, retention of that velocity down range and increased tissue destruction on impact with minimal increase in recoil and weight. It would also improve the performance of 5.56 DMR and SAW type weapons.
The heavier projectiles will require slower powder and longer barrels.
Fine for DMR, but bad for short barrel performance.
This is what I keep thinking. The thread is about thinking of an entirely new cartridge and rifle that is unhampered by the AR-15 dimensions, but I keep seeing people try and work with AR-15 mag length.
Mission drives the gear.
What should be new cartridge be able to do?
That defines the performance envelope.
A cartridge and magazine can then be designed.
After that, a weapon can be created around those two.
Requirements:
optimal 7lbs, thresh 7.5lbs
optimal 1moa, thresh 1.75moa
optimal 20% increase in ammunition weight, thresh 50%
High BC, high lethality long distance projectile, effective to 800m
Change-able LOP, and grip size (distance to trigger/safety) to accommodate 90% military aged males.
Suggestions
-two modular upper solution, IVO, 12" & 16".
-DI for longer version and a piston for shorter.
-Trigger finger bolt release ala Rem ACR other manner
-inline recoil ala AR
I'm just curious about the bolded part, especially from a parts commonality and training perspective.
The heavier projectiles will require slower powder and longer barrels.
The same is true with a larger caliber bullet. It's heavier, needs slower powder. Unless you throttle back the velocity which reduces terminal performance and range.
Fine for DMR, but bad for short barrel performance...
But how bad? Back in the 60s & 70s, the idea of a 223 from a 16 inch barrel was ludicrous. Too much velocity & performance would be lost. Heck many shooters thought you needed a 24 inch barrel for best performance. Today, shooters are banging the 223 out of 10.5 inch barrels.
Maybe 22 caliber bullets don't need to be as heavy as 90 or 100 grs to get good BC numbers. Maybe by simply extending the mag enough to let 75 or 80 gr bullets be seated out further would be enough to get velocities up to 2800 fps or more in the 5.56 case. Or 222 Magnum case. Use the long leade so higher velocities can be achieved without excessive pressure. That's how the 5.56 works. Get the BC up with a longer bullet, keep velocities up and you have a flat shooting caliber with minimal recoil and weight. The performance from a short barrel couldn't be worse than the 5.56
Nothing wrong with the M16. If Stoner had chambered it in .243 in the beginning everything would be fine.
He never chambered anything in 5.56mm.
6x47 (6mm-.222Mag) would have been ideal.
I wrote this on another site, as a comment to this article, which is sort of what this discussion touches on:
http://smallwarsjournal.com/jrnl/art/the-infantrymans-half-kilometer-reconsidered#comment-39321
---------------------
First, I believe that the "Big War" should be the driving factor in how a military force is developed/evolved, not the "Small War". If you base your TTP's and battle drills solely on fighting "small wars", you will run into issues if/when you face off with an equal enemy in terms of training and equipment.
This is not to say that fighting small wars doesn't provide good experiences for adapting and changing/improving current doctrine, but theater specific TTPs should not define how we conduct battle. «Big War» tactics should be plug and play for a «Small War» scenario.
Second, I am also a skeptic when it comes to studies that define "average engagement distances", and use these findings to argue for or against a weapon system or caliber. My reason for this is that I believe most areas will offer terrain and situations that require BOTH close quarter shooting and long range shooting. I am especially skeptical when these studies conclude that range is not important.
Third, I sometimes feel that these debates are a bit narrow in scope, in that they solely look at the individual rifleman and his weapon, instead of looking at the squad or platoon as a system.
Now, to my main point.
I believe that the way a unit is organized, in terms of weapons/effectors, should be decided through a defined capability or task requirement. For GPF, the platoon should be the smallest element that is assigned this capability or task requirement. If we remove HE systems and fire support from the equation, as well as vehicle mounted weapons, and focus solely on dismounted small arms I would argue that a platoon should be able to engage out to 800-1000 meters. That doesn’t mean all weapons systems, but some. The platoon needs to be organized and trained in a fashion that facilitates this.
If we look at this from a «Big War» perspective, small arms fire is not a big killer. Especially not the rifleman. HE really does the killing, be it from mortar, arty or air. That does not mean that the rifleman and his assault rifle/carbine is not important. On the contrary, as the rifleman with his primary weapon facilitates getting bigger guns to bear in the fight. Especially during hasty attacks or ambushes. Calls for fire take time, emplacing machineguns take time. These weapons need to be effective before fire and maneuver can start.
In defensive operations the rifleman carries out an important role by covering alternate enemy avenues of approach as well as protecting the heavier weapons.
The key to being successful in these situations, defensive operations or deliberate attacks for example, is to utilize the strengths of the weapon systems by choosing terrain that allows/facilitates this approach. If your squad’s defensive position only allows a sector of fire that extends out to 100 meters, it does not matter if your weapon system and soldier can shoot out to 600-800 meters. Sure, sometimes you don’t have a choice and you are stuck with less than ideal terrain, but if you have the opportunity during planning to maximize weapon efficiency by selecting the correct terrain, then do so!
It is said that the mission of the infantry is to locate, close with and destroy the enemy with fire and maneuver. True, but that does not mean that the sole purpose of the infantry is to do combat at breath-smelling distance. I would argue that it is much more desirable to engage and kill the enemy at distance, than it is to maneuver as close as possible before shooting.
This train of thought should be reflected in our tactics, as well as our equipment and training. Locating the enemy is often the most difficult part, and optics are key here. Monoculars, binoculars, LRFs etc all play a role, and are extremely important. And they need to be used, not just stuffed in a pack. Training our guys to be able to shoot and hit out to the effective range of the weapon system is crucial, but unfortunately neglected (at least for us). As far as weapons go, I would argue that the weapons are usually capable of doing what we need them to do. The biggest limiting factor is the shooter.
Granted, som terrain (MOUT) and enemy preparations (trenches, foxholes) etc will reduce the effectiveness of long range engagements and will probably require combat at breath-smelling distance. That’s the name of the game. We just need to make sure that we employ every system available in order to soften the target up as much as we can before we cross that threshold.
Before any change is made, I think a couple of questions needs to be answered by someone who decides doctrine:
-What role should the rifleman have as part of a squad and platoon?
-What are the capabilities needed by the rifleman to fill that role?
If someone decides that the rifleman should be able to engage point targets out to 800 meters, well, then the training and equipment should reflect that capability requirement.
At the very least, don’t change things for the sake of change.
LSAT carbine: http://www.thefirearmblog.com/blog/2010/06/29/lsat-light-machine-gun/
Except chamber it in a 6.5 to 7mm CT round to keep the ammo load light and the magazines compact enough for small hands to manipulate.
I'll reiterate, for General Purpose Forces (GPF) I see no use in anything but a Product Improved, (PIP'd) m4 upper. The current equipment capability has already exceeded the training level. SOF & specialty units would benefit.
Benito, regarding
Suggestions
-two modular upper solution, IVO, 12" & 16".
-DI for longer version and a piston for shorter.
-Trigger finger bolt release ala Rem ACR other manner
-inline recoil ala AR
I'm just curious about the bolded part, especially from a parts commonality and training perspective.
No difference in manual of arms on DI/Piston uppers.
-A DI Upper is easier to accurize at at lighter weight than a piston.
-As the envelope gets shorter a piston will be more forgiving of odd pressures, reduced dwell time, etc.
BrigandTwoFour
07-10-13, 06:50
I wrote this on another site, as a comment to this article, which is sort of what this discussion touches on....
Good post. I read that article last month, but didn't get through all the comments.
I think of it in terms of ranges and capabilities. Ideally, our people have enough training and equipment to recognize and engage a threat before that threat enters into their own capability envelope. In other words, I would want our riflemen to be able to effectively lay down fire on an enemy before their riflemen are within range of their weapons. I realize this is not historically common.
To me, the 600-1000 yard range is the realm of the 7.62 support weapons. The DMR and LMGs, with proper ammunition selection, are capable of engaging at these ranges effectively on the squad level and provide enough time for the other weapons of war to be called in.
The 300-500 is that intermediate range that may not be common to fight in, but the ability to do so with decisive power can be of huge benefit. With developments coming in the squad common optic program, and things like the Trijicon VCOG coming to market, it appears that the military is looking to provide every rifleman the capability of engaging from bad breath distance out to this 500-600 mark. While it is true that proper training is key at engaging these distances, and current training is lacking, the cartridge must be up for it.
There are many stories around here of a riflemen successfully engaging at 500-700 yards with an M4, but I would argue that the 5.56 terminal performance is greatly degraded at that distance.
In the 0-300 yard range, the more important factor becomes how quickly multiple aimed shots can be placed on an exposed target. The 5.56 is fantastic for this (it was specifically designed for it), but its demonstrated shortcomings with regards to barrier penetration have become painfully clear.
That brings me back to possible solutions. A slightly heavier bullet sitting on top of slightly more powder would provide the extra needed "oomph" at contact distances without a huge penalty in recoil or weight. This bullet would also provide better terminal effect at that 500 yard envelope. Whether this is a lengthened and heavier .22 based caliber, a 6.5, 6.8, or 7mm is academic.
I think the need has been recognized for a while. But organizational inertia as well as a mentality of "good enough" have prevented any significant movement on it. There are many other areas of infantry combat that need improvement first. As you point out, the rifleman is but a small part of the overall war.
But still, there is plenty of money wasted in areas far less productive than developing a new rifle and cartridge.
The heavier projectiles will require slower powder and longer barrels.
Fine for DMR, but bad for short barrel performance.
You also tend to need more case capacity with the slower powders.
Case neck length requirement goes up as well. The AR format cartridges (grendel/SPC) can't handle larger VLSD bullets very well due to neck length without very deep seating, which then eats up case capacity that you need for the slower powders. (boat tails are too long)
Ex: Grendel can shoot the common 140g bullets, but it is very sub optimal due to the above.
True Grendel with AA "hybrid" throats shoot well with some of the VLSD's, but only in steel mags. Some of the other throats do not work as well with VLSD's.
Even then they have to be seated deeper and may cause compressed loads. The breakthrough for Grendel was the 123g Hornady AMAX/SST. Gave very good BC's yet did not cause case length/capacity issues.
I can't help but think that if we are concentrating on the 0-300 yard range effectiveness, with occasional shots out to 500 yards, The 7.62x39 already does this pretty well. We would be reinventing the wheel. The 6.5 size cartridge has to provide an improvement in stopping power at close range (over the 5.56), and I think the main advantage would be stretching out the effective range to 700+ yards.
Rifle accuracy and optics are getting better every year, why not take advantage of that capability with a more effective long range cartridge. At the moment, the military is trying to give a varmint cartridge (.223) the most range and penetration they can get out of it, with the heavier 62gr and then 77gr bullets. Longer range is obviously a concern to the military.
Dessert Fox
07-15-13, 00:19
How about adding an anti-recoil system as employed in the AEK-971? It basically incorporates a counterweight that moves in the opposite direction of the bolt assembly. Burst/FA is unreal with almost no muzzle movement at all:
http://www.youtube.com/watch?v=gOozMdEV_AU
Requirements:
optimal 7lbs, thresh 7.5lbs
optimal 1moa, thresh 1.75moa
optimal 20% increase in ammunition weight, thresh 50%
High BC, high lethality long distance projectile, effective to 800m
Change-able LOP, and grip size (distance to trigger/safety) to accommodate 90% military aged males.
Suggestions
-two modular upper solution, IVO, 12" & 16".
-DI for longer version and a piston for shorter.
-Trigger finger bolt release ala Rem ACR other manner
-inline recoil ala AR
7mm CTA using a 110-130gr SOST type projectile. A 90gr Barnes TSX for non Hague requirements (and lets call a 170gr TTSX for subsonic applications)
Should be able to get within a 10% 77gr Mk262 rd for weight, if I am doing my math right.
25rd mag - should again be within a % or two of the 30rd USGI mag.
I think any new round not looking at CTA is a non starter. LSAT was a proof of concept - it works -- it just needed to be a better cartridge.
That round should be able to give you 800 performance - and still allow a CQBR upper to be added in a 12" or so length.
I think you would be able to get the platform easily inside 7lbs with the 16.5" barrel (which I hypothesize may be optimal for the cartridge powder burn range and bullet rane).
CTA guns are generally flipper or revolving push thru feed - so it will not be an AR -- the coolest one I have seen was a Stoner prototype that was a sealed 'revolver' mechanism. Light handy and reliable.
Recoil is very limited due to the recoil forces not operating in linear plane with the operating forces, sure you eat the recoil from the round, but not the mass of the bolt carrier etc running into the receiver.
The Polymer casing are an insulator themselves - and carry the heat out with them, not transferring it to the chamber walls. High Cyclic ROF allowed as well due to the mechanism -- think "hyper burst" al la G11 or AN-94.
Add a muzzle brake - and you can end up with a next to nil felt recoiling weapon that is light, effective and sexalicious™
wild_wild_wes
07-17-13, 15:29
Well, once you put the 1-6X optic on it, then it would be sexilicious...
constructor
07-21-13, 19:53
A lot of discussion these days is focused on the current "big 3" alternate calibers of the AR-15 platform: 6.8 SPC II, 6.5 Grendel, and 300 BLK. Each one offers various gains (or losses) when compared to the standard 5.56 NATO round used in our beloved rifles. At the same time, in other areas, the gun world is abuzz with talk about how the Army effectively shut down the individual carbine competition.
This got me thinking. Why not start a discussion about what exactly a new rifle should look like? I don't want to limit it just to the rifle, though, so let's discuss the cartridge as well. All of the stuff that we've been talking about as far as cartridge variations and rifle design has been limited by two factors:
There could be 30 days worth of good reading on this topic here-http://forums.delphiforums.com/n/main.asp?webtag=autogun&nav=messages&msg=5041.3&prettyurl=%2Fautogun%2Fmessages%3Fmsg%3D5041.3&gid=148562855
and here-http://www.quarry.nildram.co.uk/The%20Next%20Generation.htm
constructor
07-21-13, 20:14
I think the 6.5's are the way to go. They are a perfect balance of low recoil, compact size and great ballistic coefficients. They penetrate well, and have enough velocity to reach out beyond 700 yards. They are taking over in long range shooting competitions, and anyone who has hunted with a 260 rem or 6.5 Creedmore know they will do the job.
.270 is not a bad idea in something like a 270-08, but I don't think as much research and development has been done with that caliber. The 6.8SPC doesn't have the BC and reach that the 6.5's have, even the 6.5 Grendel. The bigger 270 Winchester is bulky and doesn't have as many high BC bullets developed for it, as it is not traditionally a target cartridge. The 270-08 has existed for some time as a wildcat, so someone may have more information on it.
The 300 Blackout is ridiculous for a general purpose rifle caliber, and I think the fact that you can't deer hunt in most states with a 223/556 should tell us something about that one too.
The military is moving toward green bullets. Civilians like to compare existing bullets but the military isn't going to use 6.5 Lapuas in war. A 6.5 or 6.8 green bullet can be made using the same formula in relation to diameters and have the same BC. A green bullet with a density of 8.54 would be close to solid brass or copper with a steel core. A bullet as long as a 6.5mm 139gr Lapua would only weigh 112gr and have a G7 BC of .25/G1 .500. A 6.8 with the same BC would weigh apx 116gr. Those are long for caliber bullets that would leave 1" outside the case. A 43mm (1.700" 36Gr gross capacity) case plus 1" of bullet makes that cartridge very close to the length of a 308 and it still would not produce the velocity needed.
constructor
07-21-13, 20:21
I don't even get the "Grendel does better out of longer barrels" argument. Everything does!
If the Grendel is going faster to begin with, and has better ballistic coefficients than the 6.8 or 7.62x39 in a 24 inch barrel, it will still be going faster and have better ballistic coefficients if they are all in a 14 inch barrel.
I don't know of any rifle bullet that gets faster in a shorter barrel. Please explain how ONLY the Grendel is hampered by being in shorter barrels...
Case capacity to bore area ratio and the bullets weight dictates the powder burn rate. The Grendel uses slower burning powders than the 6.8. The 6.8 using the same weight bullets will produce more velocity out of the same length barrel.
BoringGuy45
07-22-13, 10:56
I don't even get the "Grendel does better out of longer barrels" argument. Everything does!
If the Grendel is going faster to begin with, and has better ballistic coefficients than the 6.8 or 7.62x39 in a 24 inch barrel, it will still be going faster and have better ballistic coefficients if they are all in a 14 inch barrel.
I don't know of any rifle bullet that gets faster in a shorter barrel. Please explain how ONLY the Grendel is hampered by being in shorter barrels...
It's true that pretty much all rounds have better performance from longer barrels, but some rounds' performance deteriorates more noticeably in shorter barrels due to powder chosen, stability of the bullet, and other factors. Some rounds may show excellent performance in long barrels but become mediocre at best from short barrels. The 5.56 is an excellent example of this.
I wonder if the 6.5 Grendel was loaded with a faster burning powder if that would increase its short barrel performance and at the same time, allow it to keep a pretty good long range performance due to the bullet's high BC.
I also wonder if you necked up the 6.5 Grendel to take a 6.8 round of the same weight (about 125 gr), with the right powder, if you could get a muzzle velocity slightly higher than the 7.62x39mm, you could get the same energy as that round and with better external ballistics and long range performance. Sure, the BC wouldn't be as high as the 6.5 Grendel, but it would be higher than the 6.8 SPC due to the increased length of the bullet.
BoringGuy45
07-22-13, 11:54
I also wonder, if we look for a universal cartridge, could the .276 Pedersen be a good cartridge to work from? It's overall size is about that of a 7.62x39mm and thus, just slightly larger than the 7.62x45 Czech that Murray was working with. Thus, with a slightly fatter case (than the Czech round), if the Pedersen case was shorted by 7 or 8mms (down to about 43-44mms) but kept the same caliber (6.8), with modern powders I would think you could get a 130 grain bullet going at about 2600 FPS while only slightly increasing overall length from the current 5.56/6.8/6.5 etc. Plus, since the round is tapered, it would feed better too I would think, increasing reliability.
I wonder if a 6.8x44mm Pedersen would work...
The primary advantage of a tapered case is extraction when steel cases are used. The disadvantage is increased bolt thrust and require curved magazine. The case would actually be better if most of the body taper were blown out to increase powder capacity and velocity. But then it would almost be a 7mm-08
The 276 Petersen was a 28 caliber, not 27 and had a case length of 51mm with a .450" rim and base diameter. The 308 class case has a rim diameter of .473" and a base diameter of .470"
https://upload.wikimedia.org/wikipedia/commons/thumb/4/40/Pedersen_en-Block_Clip.PNG/300px-Pedersen_en-Block_Clip.PNG
If you're going to bring up .276 Pederson as a starting point I think you've also got to discuss .280 British.
The Brits tossed around a lot of the same ideas in this thread over about 15 years with all the .280 British variants. If not for US Army insistence of a .30 bullet for NATO standardization in the early 50s, we could all very well be hefting ARs chambered in .280 today.
From what I remember it was pushing 140gr @ something like 2500fps and they had workable assault rifle and LMG designs based off it.
BoringGuy45
07-22-13, 17:49
Hmmm...well, with those numbers, Mistwolf, it sounds like there wouldn't be too much advantage to using the Pedersen to start these days.
Also, in terms of the .280 British, given the size of the case, it's essentially a shortened, necked down .308 (base diameter is almost identical). It would be very difficult to carry magazines more than 20 rounds due to length. I would think that with a universal cartridge, your average rifleman would probably want at least a 25 round mag.
I wouldn't want a wider case than 7.62x39. Ballistics in the 130 at 2600 range from a 16" barrel with a .5 BC.
BoringGuy45
07-24-13, 23:22
I wouldn't want a wider case than 7.62x39. Ballistics in the 130 at 2600 range from a 16" barrel with a .5 BC.
That's true.
I don't think a .5+ BC is really necessary unless the round is going to be a universal round (replacing 5.56 and 7.62) and needs to have really long range reach due the smaller case (than the 7.62 that is).
If the two cartridge solution is the way to go, then even the Mk262 round has a BC only in the high .3 range and has plenty of long range external capabilities. So I think that if a round is going to be a pretty flat shooter out to the 400-600 yard range similar to that of the current high quality 5.56 loads (like the Mk262 and Mk318), it'll be good enough.
As I said before, I think necking up the Grendel to 6.8 might be an idea to look at. With the shorter, fatter case, you could get a longer 6.8 round than you can with the 6.8 SPC in the current magazine well dimensions, probably in the 125 gr weight area. As was stated before, 130 gr is about ideal for a 6.8 round, so 125 is pretty close. With the right powder, it could get about 2450-2500 FPS from a 16" barrel.
SomeOtherGuy
07-24-13, 23:36
As I said before, I think necking up the Grendel to 6.8 might be an idea to look at. With the shorter, fatter case, you could get a longer 6.8 round than you can with the 6.8 SPC in the current magazine well dimensions, probably in the 125 gr weight area. As was stated before, 130 gr is about ideal for a 6.8 round, so 125 is pretty close. With the right powder, it could get about 2450-2500 FPS from a 16" barrel.
Woah, 2450fps for a 125gr bullet in a 16" barrel? Dude, that's like soooo totally M1943 of you! (7.62x39mm Soviet)
There's already 6.8 SPC factory ammo pushing a 115gr bullet at 2550-2600+ fps in a 16" barrel, or a 120gr Hornady with a .4 BC at 2460fps.
I'm wondering if cartridge designers have already poked and prodded jacketed bullets in brass cases at acceptable pressure levels in just about all possible ways with little room left to reinvent the wheel.
Sorry, total buzzkill.
Lots of very interesting posts here.
I have a very extensive arms library. Many thousands of pages devoted to arms design, ballistics, development of military arms and ammunition and every possible impacting topic dating back to the invention of smokeless powder {and beyond}. All of the ballistic suggestions in this thread have been examined in-depth in the past. Nothing is new when it comes to military cartridge development. The problem is that physics doesn't change with the decades.
Terminal needs are similar, ability of a man to handle recoil doesn't change, muzzle brakes have been around "forever" it seems. There is no free lunch.
I have no military experience. None. I have, however, shot literally tons and tons of game animals and killed dozens upon dozens of livestock critters with many, many different calibers. In addition, I have a range where I can test the terminal effect of bullets and where we shoot everything from steel plate and helmets to car parts, water/wood media, slaughterhouse and game pole carcasses and bone, skulls, etc, etc, etc.
Going back almost a hundred years now, it would be easy to suggest a modern ".256" round firing a 125 grain 6.5 caliber at 2600 fps for a service rifle {easy to achieve in a <= 9 lb rifle} with a mere bullet change to 145 grain weight for a crew served machine gun. Recoil of both would be manageable and terminal effect excellent.
But.....
Taking it all into account, it really is hard for me to suggest that my idea would be worthy of nudgng out what we already have now. Superlight weight 5.56 + crew served weapons using the 7.62x51.
Regardless, as soon as a new military round IS developed and fielded, you can bet big money harsh criticism of it will immediately follow!
Lots of very interesting posts here.
I have a very extensive arms library. Many thousands of pages devoted to arms design, ballistics, development of military arms and ammunition and every possible impacting topic dating back to the invention of smokeless powder {and beyond}. All of the ballistic suggestions in this thread have been examined in-depth in the past. Nothing is new when it comes to military cartridge development. The problem is that physics doesn't change with the decades.
Terminal needs are similar, ability of a man to handle recoil doesn't change, muzzle brakes have been around "forever" it seems. There is no free lunch.
I have no military experience. None. I have, however, shot literally tons and tons of game animals and killed dozens upon dozens of livestock critters with many, many different calibers. In addition, I have a range where I can test the terminal effect of bullets and where we shoot everything from steel plate and helmets to car parts, water/wood media, slaughterhouse and game pole carcasses and bone, skulls, etc, etc, etc.
Going back almost a hundred years now, it would be easy to suggest a modern ".256" round firing a 125 grain 6.5 caliber at 2600 fps for a service rifle {easy to achieve in a <= 9 lb rifle} with a mere bullet change to 145 grain weight for a crew served machine gun. Recoil of both would be manageable and terminal effect excellent.
But.....
Taking it all into account, it really is hard for me to suggest that my idea would be worthy of nudgng out what we already have now. Superlight weight 5.56 + crew served weapons using the 7.62x51.
Regardless, as soon as a new military round IS developed and fielded, you can bet big money harsh criticism of it will immediately follow!
While not much has changed in small arms , the rest of the world evolved to an almost unreal level all this time.
The only reason we didn't see much change in small arms is because everyone wants to get that fat military contract and only develop firearms that have a chance of being adopted.
A lot has changed in materials, production technology and testing since the small arms field has been stagnant.
There's no incentive for developing new things this days. The army is only interested in 5.56mm AR-15s.
Look at LSAT. That technology could be adapted and perfected to create an almost perfect weapon system, in just a few years, if there was a will to do it.
But they just put everything on back burner and nothing useful will come out of it in the next ten years.
I'm almost certain, the next great thing in small arms will not come from the western countries, with our way of doing things.
Maybe the Chinese, or Russians will pick up on the idea and throw at it the resources and money it needs, to get it done.
Regarding LSAT -- the government is waiting for industry to come to the table with a new caliber and weapon. The systems where a proof of concept - but nothing more.
Right now in the budget climate there is no money for a new carbine -- irregardless of the capital acquisition costs for a new system, there will be the countless add on costs from equipping and supporting a new system.
I will say one thing, I do not see DoD adopting another brass cased general service weapon, and we are 10-15 years out from any new Individual Weapons Program going ahead. So companies that can and desire to spend IRD$ can and will focus on some sort of Medium cartridge CTA system. The kicker is that the .gov will not give a requirement for the ammo, PM MAS offers a lot of "we want CTA/CL ammo and we want it to do more than 5.56mm" however more is not a specific. Go to far outside 'the parameter box" and you end up with a bigger and heavier weapon than one needs.
Ideally the .gov would say:
Range
Accuracy, and accuracy at range from a given barrel length
Penetration
Terminal Affect
Low Flash
All with given quantifiable performance matrix, either in absolutes (Must be more than X or Less than X, or in a 50% greater than a M4A1 with... etc.)
For those of you who watch Future Weapons or Ultimate Weapons, if you see the PDW segment where Trey Knight is talking, the concept he talks about is like a rocket -- know how far you want to go, design the fuel, and then you can built the rocket around those requirements.
Problem is, re-equipping the entire Army with new small arms is going to be defined as an ACAT I program and to start down that path the Army has to produce an ICD that identifies a capability gap before they can even start the process of analyzing possible solutions and developing system level requirements.
It starts to be an alabatross around the neck of a PM if they ID an operational requirement that they then can't meet for an extended period of time. As I understand it, if you have a defined operational requirement, as a PM you're obligated to try and satisfy that requirement. In the current budgetary situation that you mention, do you want to be the PM that has to allocate money to satisfying a requirement that can't be met? I wouldn't want to be. If you know you can't come up with something better based on what you're seeing from industry, better to just plug along with what you have until you see something that really increases capability.
It would be a very similar situation to where the Army is at with the OH-58 replacement. They've got a defined capability gap they have to address, but really can't due to current tech limitations. In the end that's at least part of the reason we've blown a pile of money on Comanche, ARH and now Armed Aerial Scout with the only "solution" that's going to fly any time soon being a cockpit upgrade to the OH-58D.....
I'm tracking you.
The problem is where SRD is telling Industry this is where we want to be, but without quantifiable metrics.
We blew a shit ton of tax payer money on OICW and XM-8 without a defined capability...
I would argue with M855A1 ammo that the PM shop know there are issues in the M249 and M4A1 fleet - but is re-arranging deckchairs on the Titanic to cover the emperor has no clothes.
I'm tracking you.
The problem is where SRD is telling Industry this is where we want to be, but without quantifiable metrics.
We blew a shit ton of tax payer money on OICW and XM-8 without a defined capability...
The whole OICW/XM-29/XM-8 was an inexplicable boondoggle. I think part of the problem was that it was a cost plus R&D contract and not really aimed towards procurement. That plus tech limitations of all the whiz bang crap they had on it.
The only good thing to come out of that was the XM-25 which could really be an effective weapon with a little more polish on the rough edges.
I would argue with M855A1 ammo that the PM shop know there are issues in the M249 and M4A1 fleet - but is re-arranging deckchairs on the Titanic to cover the emperor has no clothes.
I have wondered if the whole "green ammo" nonsense was cover to get a more effective round without having to say that the current ammo isn't effective enough....
:cray: I was starting to like you until you thought anything nice about XM-25.
The problem as I saw it with the LFS program was that it went down 1 road instead of looking at option, secondly "Green Ammo" it is not, replacing lead with another heavy metal option is not IMHO Green, not matter how you package it.
SOST has a "Green" Lead Free Option, and Barnes Solid Copper options are also Lead Free.
When the M4 and M249 fleet is trashed by A1, I am wondering who will end up paying the piper for the actions.
:cray: I was starting to like you until you thought anything nice about XM-25.
LOL yeah yeah I know. It's probably a pipe dream. As an engineer sometimes I succumb to my inner 8 year old boy and say "That's so cool we need to make that work!" Because honestly, the idea of a man portable mag fed smart munitions dispenser is just damn cool :D
The problem as I saw it with the LFS program was that it went down 1 road instead of looking at option, secondly "Green Ammo" it is not, replacing lead with another heavy metal option is not IMHO Green, not matter how you package it.
SOST has a "Green" Lead Free Option, and Barnes Solid Copper options are also Lead Free.
Well, I have a problem going lead free in general. #1 we're just putting the stuff back where we got it from. #2 we've found the remains of Roman lead smelters that havn't leached into the soil appreciably in nearly 2000 years so something tells me there's no worry from the bullets we leave laying around anytime soon.
Not that I would turn down a TSX flavored 5.56 round....
When the M4 and M249 fleet is trashed by A1, I am wondering who will end up paying the piper for the actions.
You, me and every other taxpayer. Most PM slots are 3 year stints IIRC, so by the time the small arms inventory is shot to pieces that full bird will be off to his next task.
I'm not so much upset at the PM, its the system that allowed LFS to go careening downhill with no adult supervision asking WTF is going on...
I do not believe hope is a valid COA and so I generally despise those who feel that the solution is only XXXX away.
I'm fully tracking you on the LFS initiative - however as I understood that, it was a Congressional Mandated COA -- however foolish and misinformed (its for the children...) it was, the Army had no choice in the matter. That said, DA could/should have conducted some some awareness campaign, since it did not I believe that the good idea fairy had already beat those (who should have known) senseless with a pipewrench.
M855A1 to me is a textbook in what I would NOT look for in ammunition selection.
1) Exposed Hardened Steel penetrator to ensure magazines, uppers receiver are damaged in usage.
2) Higher or Equal to Proof Pressures to ensure premature parts failure and reliability issues. Not to mention unsafe pressure the minute ammo gets moisture on it (rain, lube on the fingers when loading...)
But I'm not PM MAS...
Maybe I should send me resume in, but maybe my adopt SOST now solution would crater too many sacred cows.
I'm not so much upset at the PM, its the system that allowed LFS to go careening downhill with no adult supervision asking WTF is going on...
There you speak truth. Being exposed to it daily, IMO DoD procurement is broken. We far too often spend massive amounts of time and money on things that don't work quite right and even if they did they don't actually meet the requirements of the end user. That said, repairing it requires the congress critters to do something sensible and what exactly do you think the probability of that is?
I'm fully tracking you on the LFS initiative - however as I understood that, it was a Congressional Mandated COA -- however foolish and misinformed (its for the children...) it was, the Army had no choice in the matter. That said, DA could/should have conducted some some awareness campaign, since it did not I believe that the good idea fairy had already beat those (who should have known) senseless with a pipewrench.
M855A1 to me is a textbook in what I would NOT look for in ammunition selection.
1) Exposed Hardened Steel penetrator to ensure magazines, uppers receiver are damaged in usage.
2) Higher or Equal to Proof Pressures to ensure premature parts failure and reliability issues. Not to mention unsafe pressure the minute ammo gets moisture on it (rain, lube on the fingers when loading...)
Yeah, ultimately a requirement is a requirement whether it's the soliders saying "we need" or congress saying "thou shalt do this." I think they really dropped the ball when conducting the analysis of alternatives. I'm convinced there was a flaw in the parameter weighting that skewed the results in favor of m855a1. Somebody didn't adequately weight wear and tear on weapons or something of that nature. Taking into account weapon wear in the total cost there's no way that m855a1 gives the best performance per $ while meeting specifications. I just don't see how it's possible...
Crane and the USMC went SOST after conducting comparative analysis.
SOST was:
Cheaper to field.
More accurate
Better terminal performance (thru most medians)
Did not steal from private industry.
Did not adversely affect reliability
Did not affect part life.
As a Taxpayer and John Q. Public I'm really hoping Congress is briefed and someone holds the ARMY to the fire on M855A1, and I generally hate political intervention...
vicious_cb
08-05-13, 09:20
Personally I do not see caseless ammo ever replacing the brass cased cartridges as the casing does provide a number of advantages I would not want to throw away. For one it acts like a heat sink preventing overheating the barrel. This makes it less than ideal for machine gun use, although overheating is usually not a concern on a carbine excluding extreme situations. Considering there is nothing between the chamber and propellant cook offs would probably be a huge problem in full auto use.
The obturation of the casing seals the chamber allowing more efficient use of the burning propellant not to mention preventing gas blow by keeping your chamber clean as well as the inside of the receiver.
As stated above if you do go to a caseless design you would to have a REALLY efficient solid propellant in order to prevent fouling the chamber causing failure to feeds.
Caseless ammo, at least the ones Ive seen, use a pretty brittle solid propellant making the ammo prone to damage. For example if the caseless cartridge were dented,deformed, or chipped how would it affect ignition?Unpredictable trajectory perhaps?
What if the cartridge failed to ignite? How would you get the misfired cartridge out without an extractor?
I'm not sold on CL ammo either -- CT ammo on the other hand does all of that and more.
Most CLA and CTA systems are flipper/rotatory chambers so a new round pushes the old one out and thus deals with the issue of unfired/misfired rounds and empties in the same manner.
Good news about LSAT. Looks like they got more money to refine and develop the system:
http://www.thefirearmblog.com/blog/2013/08/07/textron-awarded-2-million-contract-work-lsat-machine-gun-ammunition/96a9949b729e4b7d_800x800ar/
"
“HUNT VALLEY, Md. — AUGUST 6, 2013 — AAI’s Lightweight Small Arms Technologies (LSAT) team, part of Textron Systems, a Textron Inc. (NYSE: TXT) company, announced today it has been awarded a $2.05 million contract through the Department of Defense Ordnance Technology Consortiumto further innovate both its caseless and cased-telescoped lightweight ammunition and weapon technologies.
This ordnance technology initiative includes three major thrusts. It continues to refine the LSAT 5.56mmCased Telescoped ammunition and Light Machine Gun in support of an Army live fire experiment; advances development, testing and characterization of prototype 5.56mmCaseless ammunition; and extends Cased-Telescoped ammunition technologies to a 7.62mmcartridge......"
It's good they want to make a 7.62mm loading, but there's no mention of any intermediate cartridges yet.
I hope they can get the CT version perfected and then maybe they'll get it chambered in something more effective. Doing all this and fielding something chambered in the same 5.56mm, would make all mistakes made by the military in the last 100 years look like good things.
The 5.56mm system was just a proof of concept - and designed to allow an apples to apples comparison of the systems.
Now there are going for 7.62mm, which is again a bit step for an apples to apples test. This was all planned as part of phased operations, however I will say that the money ($2.05M) is peanuts when it comes to what would be required to develop and test. My guess is that AAI is looking to cash in big having a system in place for when the Army does go forward. If you have the system -- its a lot easier to scale your system to a required performance spec (or drive one yourself), than it is to play catch up when your specifications drive a requirement.
This discussion now gets to the heart of it. New calibers for service carbines are interesting but new calibers for crew served and support weapons are important.
wild_wild_wes
08-08-13, 22:48
With a new ammunition concept, the line between "service rifle" (or carbine) might blur into the PDW class for most individuals. Crew-served weapons deserve a much more powerful round.
With a new ammunition concept, the line between "service rifle" (or carbine) might blur into the PDW class for most individuals. Crew-served weapons deserve a much more powerful round.
I keep saying that the problem with 5.56mm is that it's too big, not that it's too small.
Most Soldiers need something smaller, not larger.
I keep saying that the problem with 5.56mm is that it's too big, not that it's too small.
Most Soldiers need something smaller, not larger.
This is the first I've heard this sentiment. I am interested in hearing the reasoning. I mean that honestly.
90% of people who are issued a rifle in the military aren't expected to use it except in emergencies. When they do so it will probably be at fairly close ranges both because of the nature of emergencies, and because most support Soldiers have a limited range due to poor marksmanship training and standards. The rest of the time the rifle needs to be small, light and easy to carry or stow. Small rifles have benefits also for female Soldiers, who are more common in support MOSs. A natural choice would be an 11.5" rifle, but then you have the issues common to short ARs--noise, blast, short barrel life and relatively poor ballistics. Enter a smaller caliber, like 5.56x30mm or 6x35mm. Each of those is to some extent mitigated. In the case of the 5.56x30mm, the ballistics are identical to it's larger cousin (55@2600) but you could use a lighter bullet rather than M855, which is a good SAW round but a poor choice for SBRs. The weight of loaded magazines is reduced by perhaps 20% going to a smaller cartridge and you could fit more of them on your chest. And you don't have the issue of trying to teach marksmanship with a rifle as louse as, say, a MK18. Range? Between 200 and 300m on point targets, which is plenty and lets be honest, the Army doesn't teach people to shoot past 300m unless you go to some special school anyway.
M855 was designed for performance at more than 450m anyway, inside of which M193 outperforms it. There is no reason to be using it in carbines.
vicious_cb
08-09-13, 02:37
90% of people who are issued a rifle in the military aren't expected to use it except in emergencies. When they do so it will probably be at fairly close ranges both because of the nature of emergencies, and because most support Soldiers have a limited range due to poor marksmanship training and standards. The rest of the time the rifle needs to be small, light and easy to carry or stow. Small rifles have benefits also for female Soldiers, who are more common in support MOSs. A natural choice would be an 11.5" rifle, but then you have the issues common to short ARs--noise, blast, short barrel life and relatively poor ballistics. Enter a smaller caliber, like 5.56x30mm or 6x35mm. Each of those is to some extent mitigated. In the case of the 5.56x30mm, the ballistics are identical to it's larger cousin (55@2600) but you could use a lighter bullet rather than M855, which is a good SAW round but a poor choice for SBRs. The weight of loaded magazines is reduced by perhaps 20% going to a smaller cartridge and you could fit more of them on your chest. And you don't have the issue of trying to teach marksmanship with a rifle as louse as, say, a MK18. Range? Between 200 and 300m on point targets, which is plenty and lets be honest, the Army doesn't teach people to shoot past 300m unless you go to some special school anyway.
M855 was designed for performance at more than 450m anyway, inside of which M193 outperforms it. There is no reason to be using it in carbines.
The concept has already been invented and fielded, it called the .30 M1 carbine. :)
Although I would agree that something like the KAC PDW should be fielded to non-combat personnel though I do not see the military ever adopting it with the current budget situation.
A 5.56x30mm would be shorter and have half again the range and twice the accuracy of the M1 Carbine, but it would be a similar concept. Likely you'd also see a lot of them with infantrymen, the reduction in weight could be used to carry more ammo on belts and mortar rounds.
As to the budget, it's not as insurmountable as you might believe, because these items have service lives and can be replaced in time. The new rifle (if AR pattern) could be cheaper than the M4 it replaces and the ammo would be marginally cheaper (less material). They could be phased in as older rifles are phased out.
If Congress had some balls, they'd authorize people to take possession of an M16 from the CMP upon presentation of proof of payment for 2-3 new carbines for the service. But we'll never see that kind of bravery from Congress.
A 5.56x30mm would be shorter and have half again the range and twice the accuracy of the M1 Carbine, but it would be a similar concept. Likely you'd also see a lot of them with infantrymen, the reduction in weight could be used to carry more ammo on belts and mortar rounds.
As to the budget, it's not as insurmountable as you might believe, because these items have service lives and can be replaced in time. The new rifle (if AR pattern) could be cheaper than the M4 it replaces and the ammo would be marginally cheaper (less material). They could be phased in as older rifles are phased out.
If Congress had some balls, they'd authorize people to take possession of an M16 from the CMP upon presentation of proof of payment for 2-3 new carbines for the service. But we'll never see that kind of bravery from Congress.
For the military, this could create a logistics nightmare.
90% of people who are issued a rifle in the military aren't expected to use it except in emergencies. When they do so it will probably be at fairly close ranges both because of the nature of emergencies, and because most support Soldiers have a limited range due to poor marksmanship training and standards. The rest of the time the rifle needs to be small, light and easy to carry or stow. Small rifles have benefits also for female Soldiers, who are more common in support MOSs. A natural choice would be an 11.5" rifle, but then you have the issues common to short ARs--noise, blast, short barrel life and relatively poor ballistics. Enter a smaller caliber, like 5.56x30mm or 6x35mm. Each of those is to some extent mitigated. In the case of the 5.56x30mm, the ballistics are identical to it's larger cousin (55@2600) but you could use a lighter bullet rather than M855, which is a good SAW round but a poor choice for SBRs. The weight of loaded magazines is reduced by perhaps 20% going to a smaller cartridge and you could fit more of them on your chest. And you don't have the issue of trying to teach marksmanship with a rifle as louse as, say, a MK18. Range? Between 200 and 300m on point targets, which is plenty and lets be honest, the Army doesn't teach people to shoot past 300m unless you go to some special school anyway.
M855 was designed for performance at more than 450m anyway, inside of which M193 outperforms it. There is no reason to be using it in carbines.
Respectfully, that is not an argument for a smaller caliber weapon service wide, it is an argument to have to classes of weapons:
-Service rifle/carbine for front line troops
-PDW/SBR for support personnell
Wasn't that the idea with the M4 initially, to issue it to support personnell?
As I stated previously, the "infantryman" is supposed to do a specific job as part of a squad and platoon. Identify this job, and it's requirements, and you can choose caliber and platform. Training also needs to be revised to reflect whatever capability requirement is put forth.
Limiting a shooter's engagement envelope due to the notion that most guys don't use their gun anyways isn't the correct path, IMO. If training is changed, you will now lack performance capability due to a less than ideal gun/caliber combo.
oh you and your logic... ;)
I agree 110% with Arctic1
Look at the whole NATO PDW concept - it was fatally flawed from the get go. We do not want is this day of asymmetrical threats to give "non combat" arms a BB gun.
If you look at Iraq and Afghan, a lot of combat was conducted by convoy personnel who where not combat arms forces -- using the NATO PDW logic these troops would be running around with a glorified pistol.
I'm okay with a PDW, as long as it shoots an effective long gun cartridge. Colt's MARS 5.56x30 round was a look to a while back, however 5.56mm ammo generally is velocity dependent - and anyone wanting to go back to M193 needs to give their head shake. I think our (KAC) 6x35 system with a 65gr Barnes TSX bullet would be a pretty good setup for a PDW in that respect.
However....
I still think CTA is they way forward.
6mm CTA PDW <5LB 8" barrel (300m range band)
7mm CTA IC/LSW 7lb IC with 16" barrel 9lb LSW 16" barrel (800m range band)
8mm CTA GPMG/HSW 17lb GPMG 12-13lb HSW (1600m range band)
12mm CTA HMG (3000m+ range band)
Main advantage of CTA is weight and cleaner and cooler firing. Plus when you have a new ammo - you can take advantage of the advances is small arms bullet designs as well.
wild_wild_wes
08-09-13, 12:21
Kevin, do you think CTA would perform accurately enough for precision rifles?
Say maybe your 7mm for DMs and the 8mm for Snipers?
BoringGuy45
08-09-13, 12:26
For the military, this could create a logistics nightmare.
My thoughts too. Logistics is the reason we still have the 5.56 instead of upgrading to the 6.8 or even 300 BLK. I do wonder if looking at upgrading weapons will be taken more seriously after Afghanistan winds down.
.40 carbine, carbon fiber stock, Stainless steel insert, 17" barrel, m1 action.
Respectfully, that is not an argument for a smaller caliber weapon service wide, it is an argument to have to classes of weapons:
-Service rifle/carbine for front line troops
-PDW/SBR for support personnell
Wasn't that the idea with the M4 initially, to issue it to support personnell?
I should have been more clear, the need for a larger weapon for infantrymen than the large PDW calibers is obvious. 5.56mm performs well in this role, in it's balance of range, terminal effect and weight. If a larger caliber were adopted for infantrymen you essentially would have to adopt a PDW round, because carrying a 7mm rifle and ammunition just doesn't make sense for most Soldiers.
Limiting a shooter's engagement envelope due to the notion that most guys don't use their gun anyways isn't the correct path, IMO. If training is changed, you will now lack performance capability due to a less than ideal gun/caliber combo.
Likelihood of an engagement beyond 300m is how common? Likelihood that the Army trains it's Soldiers to shoot beyond that, Infantrymen excepted? For that matter, likelihood that the Navy and AF engage at further than 300m? The USMC has shown a willingness to train at extended range and this might not be a solution for them (they certainly wouldn't accept it) but they are the exception rather than the rule. In any case how common is it for support troops to engage beyond the range or an 11.5" 5.56mm?
For the military, this could create a logistics nightmare.
Meh. Ammunition is a very small part of what a logistician does. The issue isn't getting it to the front, or to the COP, it's crossloading after a fight on day 22 of a 9 day patrol.
Look at the whole NATO PDW concept - it was fatally flawed from the get go. We do not want is this day of asymmetrical threats to give "non combat" arms a BB gun.
If you look at Iraq and Afghan, a lot of combat was conducted by convoy personnel who where not combat arms forces -- using the NATO PDW logic these troops would be running around with a glorified pistol.
I'm okay with a PDW, as long as it shoots an effective long gun cartridge. Colt's MARS 5.56x30 round was a look to a while back, however 5.56mm ammo generally is velocity dependent - and anyone wanting to go back to M193 needs to give their head shake. I think our (KAC) 6x35 system with a 65gr Barnes TSX bullet would be a pretty good setup for a PDW in that respect.
The 5.56x30 and 6x35 are a world apart from the NATO PDWs. I believe that performance of both would be relatively similar given equal bullets, with a nod on bullet weight to the 6mm and the 5.56 being shorter and compatible with existing silencers and bullet production lines. I wouldn't want to go back to M193... if starting from scratch I would spec a 55gr FMJ, a 55TTSX and an RRLP load, all engineered to minimize trajectory and POI differences. I'd want a BC somewhere in the .275 range, IIRC it would go subsonic at about 500m, which is 2/3 the range of an M4. Ideally you'd be able to use all three without mandatory rezeroing because the grouping of each load combined with it's POI shift from zero would fall within an acceptable tolerance.
Agree on the import of developing telescopic ammo, though it's most important in machineguns.
My thoughts too. Logistics is the reason we still have the 5.56 instead of upgrading to the 6.8 or even 300 BLK. I do wonder if looking at upgrading weapons will be taken more seriously after Afghanistan winds down.
Don't confuse logisitcs and budget. If the military WANTED a 6.8, they would prioritize it, cancel a half a dozen fighters and a ship or two and buy new weapons. They don't want it, for reasons that aren't entirely bad...
6.8 and .300BK are not general issue calibers. .300BK and 6.8 don't have longer range usage ability that 5.56mm does.
Look at the bolt face of a 6.8 gun and tell me you think that the bolt will last over 5k rounds - or that a SAW will be effective to 800m with that round. It's not happening.
When I say 7mm CTA -- look at the performance characteristics of 7mm Murray (UAIC) - it is easily handled by the average soldier.
I'm not talking about a 7mm RemMag setup here.
CTA has been done for sniping before - it can be that accurate.
I cannot share specifics on the round or program however.
RyanB -- agree with your comment about 5.56x30 and 6x35 (I'd lump .300BK with its 7.62x35 round in there too) however the Army is not going to adopt another brass case gun -- trust me here.
Another platform must be revolutionary -- or else we are looking at another M4 PIP (which you can do with those PDW round above - but you still are constrained by the M16FOW architecture)
If you can achieve performance of the 5.56x30 or 6x35 in a CTA rifle, I have no objections to using it. I just don't know enough about it to judge. My brother has seen LSAT at the trade shows and won't shut up about it, but I haven't.
The SAW round should have more ass to it. And yes, I would have serious reservations about the 6.8 bolt in an AR sized rifle. I'd prefer a 6.5 or 7x43 in a purpose built rifle. I suspect that there are gremlins in the 6.8 AR15 bolt that haven't been discovered because of the cost of the ammunition.
.300BLK is out because it is too heavy. As I understand it, JSOCs interest in it is related to it's performance with subsonic ammunition anyway, though someone with a yellow name is welcome to call me out for saying that.
BoringGuy45
08-09-13, 15:58
True, but as the 6.8 was developed, it was second in the line of quick fixes for the shortcomings of the 5.56. I have no doubt that the bolt could be redesigned in some way or another to make the face stronger. Obviously, it was also designed to increase terminal performance in the 0-300 meter range and have better performance against intermediate barriers. My understanding is that it's capable of longer range, but that its short projectiles make it marginal for BC. One of the reasons why I suggested a 6.8 in a shorter, slightly fatter case, such as a necked up 6.5 Grendel a few posts back. With the shorter case length, you could get the same case capacity and bullets of the same weight in a longer, more streamlined package. Such a bullet could probably have external ballistics falling somewhere between the Grendel and the SPC with terminal performance superior to the Grendel.
All that said, if CT rounds can be all that I'm reading that they are, and give 7x46 Murray performance in packages lighter than even what's currently available, it sounds like a dream.
Having a universal cartridge is great for logistics and for shared use on the battlefield. Obviously, a round that's going to make an assault rifle more powerful but a GPMG lighter is going to greatly increase the weight of riflemen. It sounds like the CTRs solve this problem.
7mm CTA would be too large and heavy to issue to everyone. It's going to recoil too much for some Soldiers, etc. If you go to a bigger caliber you need to match it with a smaller one as well.
The other issue is that if you have the same caliber in MGs and magazine rifles, you will end up sharing ammo. That means low quality ammunition for the magazine rifles, despite the fact that from a logisticians perspective the two weapons don't even share ammunition, since once comes on clips and the other comes in belts.
BoringGuy45
08-09-13, 18:05
How large are the CT rounds? They look pretty fat; almost like 20 gauge shells. I would think that this would add a lot of bulk and very long magazines.
wild_wild_wes
08-09-13, 23:21
I do wonder if looking at upgrading weapons will be taken more seriously after Afghanistan winds down.
Probably the opposite. Interest in small arms always falls off after a war winds down.
A lot of discussion these days is focused on the current "big 3" alternate calibers of the AR-15 platform: 6.8 SPC II, 6.5 Grendel, and 300 BLK. Each one offers various gains (or losses) when compared to the standard 5.56 NATO round used in our beloved rifles. At the same time, in other areas, the gun world is abuzz with talk about how the Army effectively shut down the individual carbine competition.
]
BrigandTwoFour though this is a fun thought experiment it misses the point that most people who haven't served in the Infantry don't get, it's not about the round, any round, that is why an Infantry platoon carries a variety of weapons and munitions. Infantry combat is about maneuver and fire superiority. Also what makes the M4 a great weapon today is the stuff we bolt to it. The various things I had on my M4 and my helmet cost about 5 times as much as the rifle, and our bolt-ons just keep getting better. Until we have a true revolution in small arms the NATO 5.56 and 7.62 will do just fine.
Ammo is tracked by DODIC. 5.56 in boxes and 5.56 on links is completely different for logistical purposes.
Moving to three rounds (a small 6MM for 95% of individuals, a 7MM for infantry SSG and below as well as LMGs, and an 8MM and maybe something larger) would simplify logistics. You'd have the same number of DODICs, but the ammunition would be lighter, smaller and cheaper.
jerrysimons
08-11-13, 19:51
Sorry, but what is 7mm cta?
CTA means cased telescopic ammunition.
Use google.
7MM CTA doesn't exist. Yet.
constructor
08-12-13, 16:47
5.56, 7.62x39, 6.5 or 6.8 x45, 7.62 nato
120gr green bullet, G7 BC of .25 will reach apx 2700-2750fps from a 16"barrel.
Ammo 20% lighter than the 308 saves 1lb/100.Apx 32% less recoil than the 308.
High BC green bullets are long, used in a brass case large enough to propel them at needed velocities result in a 2.6" + COAL. Caseless ammo will need to have 40-42gr capacity to push a 120gr bullet fast enough to match the exterior ballistics of the 308.
http://m.b5z.net/i/u/6132121/i/6.8x45comp.jpg
BC of .25 isn't very high
It's a G7 BC. Double it and you'll have a rough starting point for comparison.
constructor
08-12-13, 20:04
It's a G7 BC. Double it and you'll have a rough starting point for comparison.
Right.
This exact same topic is being discussed on several different forums.
If we consider 1 cartridge to replace both the 7.62 NATO and the 5.56 in LMG, DMR and carbine use because of A'stan they will want the exterior ballistics to match the 7.62 NATO in order to engage the enemy using the 7.62x54.
A 6.5 or 6.8 green bullet with a density of apx 8.54 will need to be close to 1.38" long and 115-120gr to reach a G7 .25 BC/G1 .500 BC. That is longer than a 6.5mm 139gr Lapua.
Most think a 7mm green bullet that reaches a .25BC will weigh too much and not make the wanted 20% ammo weight reduction from the 308. The bullet will also need to be apx 1.42" long or 5 calibers. Then you must consider the more that bullet weighs the more powder and larger case it will take to push it at the velocity needed to match the ballistics of the 7.62NATO. Caseless/poly is a big ? at this point, no one really knows how much it will weigh or how much extra room it will take up until the final usable product is designed.
Should all support troops use PDWs or continue to use the 5.56?
Should door kickers continue to use the 5.56 M4 or get something more powerful? Many agree that Nato forces need a lighter LMG. Many also seem to think they need something with more range and power than the 5.56 at the same time...The range of the 308 but lighter.
vicious_cb
08-14-13, 05:56
Right.
This exact same topic is being discussed on several different forums.
If we consider 1 cartridge to replace both the 7.62 NATO and the 5.56 in LMG, DMR and carbine use because of A'stan they will want the exterior ballistics to match the 7.62 NATO in order to engage the enemy using the 7.62x54.
A 6.5 or 6.8 green bullet with a density of apx 8.54 will need to be close to 1.38" long and 115-120gr to reach a G7 .25 BC/G1 .500 BC. That is longer than a 6.5mm 139gr Lapua.
Most think a 7mm green bullet that reaches a .25BC will weigh too much and not make the wanted 20% ammo weight reduction from the 308. The bullet will also need to be apx 1.42" long or 5 calibers. Then you must consider the more that bullet weighs the more powder and larger case it will take to push it at the velocity needed to match the ballistics of the 7.62NATO. Caseless/poly is a big ? at this point, no one really knows how much it will weigh or how much extra room it will take up until the final usable product is designed.
Should all support troops use PDWs or continue to use the 5.56?
Should door kickers continue to use the 5.56 M4 or get something more powerful? Many agree that Nato forces need a lighter LMG. Many also seem to think they need something with more range and power than the 5.56 at the same time...The range of the 308 but lighter.
6mm 90gr projectiles have .400 BC. I believe someone made a 6mm wildcat based on the old 6mm SAW cartridge which looked pretty promising. While its too long to fit in an AR form factor it does fit the bill for an individual weapon for 0-800m.
http://img52.imageshack.us/img52/8941/dsc00781copy.jpg
(L-R) Sierra 70grMK,85grHPBT,90grFMJ,Hornady 87grHPBT,Berger 90grMTBT,6.2mmOCC w/ Sierra90grFMJ
https://www.m4carbine.net/showthread.php?t=45238&page=2
SomeOtherGuy
08-14-13, 09:18
120gr green bullet,
I know the Army is on a "green bullet" kick. To me it is just so much bullshit. After they stop using any depleted uranium rounds in anything, only then, maybe, does lead matter. Oh, yeah, maybe also after they start using "green" explosive filings, "green" incendiaries, etc. The "green bullet" must be someone's pet project, a totally meaningless stupid gimme to ignorant environmentalists trying to look good on TV.
Oh, and if it really does make sense, why don't we see all law enforcement - at least all federal LE - going to lead free bullets? They practice here, and any hot shooting they do is here in the USA too. And it's a lot easier to make a decent lead-free pistol bullet than a decent lead-free rifle bullet.
(Not attacking you Constructor, just the concept of the "green bullet")
Lead contamination amongst trainers and range staff is becoming an issue.
I find that hard to believe, seeing as EVERY test done by the Norwegian Defence Research Establishment prove that there is way more copper, zinc and other metal particles in the air than lead after a round is discharged, and that there is extremely little lead absorbed by groundwater after the lead goes in the ground.
Metal fume fever is real, and can be a result of inhaling or ingesting particles, but personnell health was never a concern when our military switched to environmental ammo. The environment was.
Our switch was a result of our government's environmental policies, to prove that the military could show environmental considerations when developing the new main training area and firing range maybe 10 years ago. That was the only reason.
We even had personnell suffer from metal fume Fever WITH Our environmental ammo, because the concentration of metal particles was a lot higher than the ammunition containing lead. Still, it only happened at ranges with very bad circulation and high round counts.
I should put it differently. The Army claims that they have had issues with lead exposure among trainers and range staff. They either do, or they are lying about it. The funny thing is that the problem is in the primer, not in the bullet.
My base's indoor range has washing machines in it for ROs and instructors. USAF base.
Airborne Lead contamination is a deal with the primers not the round, other than ranges that use a lot of .22LR subcal training.
Ok. We use lead free primers in our ammo.
Still, there will be metal particles in the air when discharing the firearm. The NDRE wrote a thorough report on this, in regards to the health issues experienced by some, but it's in Norwegian unfortunately. The cause was higher concentration of copper and zinc particles during discharge with the environmental lead-free ammo.
Here is the abstract:
English summary
The Norwegian Defence Research Establishment (NDRE) was assigned by the Norwegian Defence Logistic Organization to elucidate the reason for the reported health hazard associated with HK416 assault rifle practicing, and to perform a health risk assessment and to propose appropriate means of risk reduction.
Ammunition contains compounds that can pose a health risk. Hence, it is important that use of ammunition is carried out in a manner that prevents personnel from being exposed at unacceptable levels. After practicing with the assault rifle HK416, recently obtained by the Norwegian Defence, soldiers have from time to time complained about health problems such as coughing, fever, chills, headache, nausea, myalgia, and sore throat.
Tests have been carried out in order to elucidate whether the following aspects are of importance to the observed health effects:
•The design of the weapon
•Ammunition content and mode of operation
•Implementation of weapon practice
In order to accomplish the tests, four weapons were tested, with two types of ammunition; lead free and with lead. These weapons were included in the test: AG3, Colt C8, HK416K and HK416N.
The tests included quantification of personnel exposure and of particles and compounds from the different weapons and ammunitions. In addition a literature study of the toxicology of relevant compounds was carried out in order to relate cause and the observed health effects.
A matching of the symptoms with the compounds in gun smoke from HK416, indicates that the health effects are caused by copper and zinc. These compounds were found at high concentrations, particularly after firing 5,56 x 45 mm lead free ammunition. Inhalation of copper and zinc are known to cause metal fume fever which is characterized by flue like symptoms.
Means of risk reduction should be carried out. These should be aimed at reducing the exposure for the shooter. This would typical be ventilation of the stand, increased distance between the shooters, etc.
A link to the document:
http://www.ffi.no/no/Rapporter/09-00820.pdf
sinlessorrow
08-16-13, 14:08
A question about CTA. Isnt the ammo bulkier than standard ammo? Not in the weight/length area but diameter wise?
I also know the operating systems seems pretty complicated with the whole rotating chamber and that well....AAI's carbine is insanely large looking compared to modern firearms.
How would one get a CTA type round to work in a compact package if a rotating chamber and push through ejection is needed? How does CTA perform suppressed?
http://www.thefirearmblog.com/blog/wp-content/uploads/2013/01/lsat_carbine-tm-tfb.jpg
Short answer to the diameter issue is no -- there is no case neck per say, so while the chamber wall is a little thicker in a CTA round to system generally use a similar diameter to brass cased ammo.
Many folks have taken different swings at the revolving chamber or semi-supported chamber flipper concepts.
With push-through/ push-out chambers it depends on how many cylinders you have and the offset of the chambers, as well as rotational direction.
Gene Stoner did a super neat CTA revolving chamber SMG/PDW gun in the 70's that was pretty small.
If you do a 90 degree horizontal - vertical rotational chamber like the G11 system did - you can have thin, but need room for the next round to be presented and enter the chamber, if you have a revolver cylinder revolves in a circular plane linearly to the bore line, you get more width - but limited height.
A semi-supported flipper can be very small, but the lockup is always suspect to failure.
Remember the AAI Carbine was just designed as a proof of concept - but not envisioned as an issue weapon (at least as I understood the JSAAP briefings).
The neat sort of thing about the push thru revolvers is they can be a Bullpup design without the many failings of bullpup weapons.
sinlessorrow
08-16-13, 14:37
Short answer to the diameter issue is no -- there is no case neck per say, so while the chamber wall is a little thicker in a CTA round to system generally use a similar diameter to brass cased ammo.
Many folks have taken different swings at the revolving chamber or semi-supported chamber flipper concepts.
With push-through/ push-out chambers it depends on how many cylinders you have and the offset of the chambers, as well as rotational direction.
Gene Stoner did a super neat CTA revolving chamber SMG/PDW gun in the 70's that was pretty small.
If you do a 90 degree horizontal - vertical rotational chamber like the G11 system did - you can have thin, but need room for the next round to be presented and enter the chamber, if you have a revolver cylinder revolves in a circular plane linearly to the bore line, you get more width - but limited height.
A semi-supported flipper can be very small, but the lockup is always suspect to failure.
Remember the AAI Carbine was just designed as a proof of concept - but not envisioned as an issue weapon (at least as I understood the JSAAP briefings).
The neat sort of thing about the push thru revolvers is they can be a Bullpup design without the many failings of bullpup weapons.
Thanks Kevin. See now that is a bullpup I would love. Has there been any tests on suppressing something like this?
CTA has been suppressed. It is much cleaner to run, as the chamber does not get fouled by propellants in the same manner as brass case guns due to the different operations cycle.
sinlessorrow
08-16-13, 14:53
CTA has been suppressed. It is much cleaner to run, as the chamber does not get fouled by propellants in the same manner as brass case guns due to the different operations cycle.
Appreciate the info. I would love to see a 6mm-7mm CTA bullpup one day, one that is a true bullpup without the cons that come with most currently.
From what I understand its almost possible to put the mag in fromt of the trigger and still have most of the action at the rear.....kind of like a intermediate rifle lol. I believe thats what AAI did in the picture I posted, that rifle had like a 18" barrel.
Either way hopefully I will see CTA become fleeted....though I have a feeling it will never make it to the civilian market.
wild_wild_wes
08-16-13, 15:09
A question about CTA. Isnt the ammo bulkier than standard ammo? Not in the weight/length area but diameter wise?
I also know the operating systems seems pretty complicated with the whole rotating chamber and that well....AAI's carbine is insanely large looking compared to modern firearms.
How would one get a CTA type round to work in a compact package if a rotating chamber and push through ejection is needed? How does CTA perform suppressed?
http://www.thefirearmblog.com/blog/wp-content/uploads/2013/01/lsat_carbine-tm-tfb.jpg
Here is a vid of LSAT chambering and firing. Doesn't look too complex.
http://www.youtube.com/watch?v=PHkW-RKBXK4#at=29
wild_wild_wes
08-16-13, 15:26
Textron Inc. Awarded $2 million Contract To Work on LSAT Machine Gun Ammunition
HUNT VALLEY, Md. — AUGUST 6, 2013 — AAI’s Lightweight Small Arms Technologies (LSAT) team, part of Textron Systems, a Textron Inc. (NYSE: TXT) company, announced today it has been awarded a $2.05 million contract through the Department of Defense Ordnance Technology Consortium to further innovate both its caseless and cased-telescoped lightweight ammunition and weapon technologies.
This ordnance technology initiative includes three major thrusts. It continues to refine the LSAT 5.56mm Cased Telescoped ammunition and Light Machine Gun in support of an Army live fire experiment; advances development, testing and characterization of prototype 5.56mm Caseless ammunition; and extends Cased-Telescoped ammunition technologies to a 7.62mm cartridge.
The 7.62mm cased-telescoped cartridge will incorporate mature lightweight ammunition technologies successfully demonstrated in the 5.56mm LSAT cartridge.
http://www.thefirearmblog.com/blog/2013/08/07/textron-awarded-2-million-contract-work-lsat-machine-gun-ammunition/
sinlessorrow
08-16-13, 15:35
Here is a vid of LSAT chambering and firing. Doesn't look too complex.
http://www.youtube.com/watch?v=PHkW-RKBXK4#at=29
I have a feeling theres more than is easily visible. I have to wonder how complex the operating system is since there is no bolt.
I could also be vehry wrong on complexity though. I wish they would ditch the caseless and pour all their effort into the CTA stuff.
Ehrhart, T. (2009). Increasing Small Arms Lethality in Afghanistan:
Taking Back the Infantry Half-Kilometer.
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA512331&Location=U2&doc=GetTRDoc.pdf
That was a really good read. Thanks.
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.