View Full Version : Why did, or will you choose the 6.8?
phoenixtac
09-19-06, 16:42
I'm currently doing my D.D. on the 6.8 SPC Cartridge, do any of you have experience shooting, or testing the cartridge?
What would you consider it's maximum range, and how are the groups at that range?
Lastly...what length barrels did you shoot it with, and velocities recorded?
That about sum's it up, and thank you for the information in advance.
I can barely afford to shoot the amount of 5.56MM I like... for me switching to 6.8MM just ain't happening... would make it even more expensive.
Just my take
The main reason I decided to go with a 6.8 is because of its size, and even that is two fold.
1: Its bigger than a 223/556
2: It still fits in a 223 sized AR-15
The 6.8 is just a neat caliber. It gives me the same traj as a 77gr 223 and a 308 168gr SMK. So its range is just as good as a 38, to an extent.
So the 6.8 will have pretty much the same range as a 223, it will just hit harder. Though if you handload a SMK fairly hot, I think you might get a better traj than a 223.
My gun was built by Grant.
16.1 Noveske brl
Troy 12.0
With Rem OTM ammo I am getting right at 1.25MOA @ 100 yards with it. Handloads will get better than that. The recoil is subjective. My gun has a vortex fh, but I am going to swap it out for a MSTN brake. The recoil isnt bad, not much more than the 223, I just want to stop the muzzle rise.
http://coloradomultigun.com/misc/sgn_68spc.pdf
that link will tell you pretty much everything you want to know.
phoenixtac
09-20-06, 16:47
Thanks for the info so far, I will read the link when I get more time.
More retained energy downrange in the same sized weapon as 5.56mm. It's that simple. I give up three rounds in the mag and a negligable increase in recoil. At the rate 5.56mm ammo is increasing in price, it's not that much more expensive to shoot 6.8mm SPC (apples to apples; you're not going to find surplus 6.8mm).
Stephen
A better BC (than 5.56) out of a short bbl. That's my reason (10.3" bbl).
Sean
With ammo prices going through the roof I don't see myself leaving 5.56mm any time soon.
If anything my next move will be to .308.
Submariner
09-23-06, 15:15
I'm seriously thinking of getting OUT of 7.62mm because it is a service round and 6.8 SPC might fall through the cracks on the next bout of gun-grabbing (if ammo taxation is part of it; Moynihan once proposed taxing .45 ACP, 9mm, 5.56mm, 7.62mmX39, and 7.62mmX51.) The price differential between good 5.56mm (Black Hills) and 6.8 SPC is narrowing. The 6.8 SPC requires less powder per round than 7.62mm and bullets are SMK's are about 75% of 7.62mm varieties when reloading costs are considered. Plus, M1A's (my 7.62mm of choice) have a whole different manual of arms.
Knowing what I know today (what has been posted above), if I were just starting out, I would probably go with 6.8 SPC and a dedicated .22LR upper for practice.
I'm seriously thinking of getting OUT of 7.62mm because it is a service round and 6.8 SPC might fall through the cracks on the next bout of gun-grabbing (if ammo taxation is part of it; Moynihan once proposed taxing .45 ACP, 9mm, 5.56mm, 7.62mmX39, and 7.62mmX51.) The price differential between good 5.56mm (Black Hills) and 6.8 SPC is narrowing. The 6.8 SPC requires less powder per round than 7.62mm and bullets are SMK's are about 75% of 7.62mm varieties when reloading costs are considered. Plus, M1A's (my 7.62mm of choice) have a whole different manual of arms.
Knowing what I know today (what has been posted above), if I were just starting out, I would probably go with 6.8 SPC and a dedicated .22LR upper for practice.
Very thought provoking. The one thing that's kept me away from the 6.8 is the cost, however, in light of the narrowing of the gap and the fact that the "antis" will not be so generous the next go around (read more thorough), the build I've been planning may just take a new direction. Don't think I'll give up on the 5.56 though.
QuietShootr
09-23-06, 16:52
Two words:
Bolt breakage.
Anyone got data on the parts failure of 6.8s run hard?
phoenixtac
09-24-06, 08:45
Two words:
Bolt breakage.
Anyone got data on the parts failure of 6.8s run hard?
Very interesting comments from everyone (thank you), I would really like to hear more about failures, and any bolt breaking issues.
Submariner
09-24-06, 11:49
Two words:
Bolt breakage.
Anyone got data on the parts failure of 6.8s run hard?
Those two words are why I haven't (yet) put money into 6.8SPC. No matter how good the cartridge, it is no good if you can't keep the gun running over time.
Two words:
Bolt breakage.
Anyone got data on the parts failure of 6.8s run hard?
Yes, from more than a couple reliable sources, but anytime I bring them up the "experts" quickly tell me I'm full of shit, and the issues were faulty parts and not the cartridges fault. But - those issues were with the cartridges loaded to the specs of what they were supposed to be, not the lower pressure round they ended up as.
The ONLY reason to buy a 6.8 is bacause you want one. If you sleep better at night because you convinced yourself you have a more deadly carbine, good for you, enjoy your hobby.
The only bolt breakage data I had was from the earlier spec'd ammo
Anyone ask Zak what life he is getting? However I hardly view replacing a bolt at a rate that is about twice the 5.56mm to be a deal breaker.
Submariner
09-24-06, 14:50
However I hardly view replacing a bolt at a rate that is about twice the 5.56mm to be a deal breaker.
Doesn't that sorta' depends on if we are talkin' DPMS- or Colt-made bolts?;)
Would it not depend also on the price and availability of said bolt?
At what round count do you replace a 5.56mm bolt?
This reminds me of the "Perfection" of 9mm Glocks:rolleyes: being lost when the design was scaled up into larger calibers.
The ONLY reason to buy a 6.8 is bacause you want one. If you sleep better at night because you convinced yourself you have a more deadly carbine, good for you, enjoy your hobby.
An Active Duty SF Sergeant used to publish a quarterly entitled, The Resister. He once included a political cartoon of a carbine in a case with a glass front with a hammer attached to the frame. Under it were the words "BREAK GLASS IN CASE OF TYRANNY". Oh, it is a hobby; nevertheless, it is much, much more.
Oh, it is a hobby; nevertheless, it is much, much more.
I’m sure a lot of folks lose sleep over just that. Not me. When it comes to that, the willingness of the individual will be what matters. The caliber of the weapon is insignificant, be it a .22 revolver or a U-Haul full of fertilizer and diesel fuel.
You need to do/buy/train as you see fit. When the times comes you'll be responsible for your decisions.
phoenixtac
09-24-06, 21:22
And for those of you who already have a 6.8, what kind of accuracy did you get, and at what ranges??
And for those of you who already have a 6.8, what kind of accuracy did you get, and at what ranges??
With commercial ammo ( Remington, Hornady, SSA Xtreme ) you can expect to get 1.25 MOA @ 100 with an good AR. With a bolt gun it will be better.
With handlaods, and SSA matchkings You can probably get pretty close to 1 MOA @ 100. At least thats what its been for me so far.
My 6.8 has a 16.1 noveske, and a 6x scope, and I know the trigger puller isnt the best. I would assume that if you had a 20 or 24" brl it might be more accurate.
Do grendel guns have the around the same ammount of bolt failures also?
QuietShootr
09-26-06, 20:56
The only bolt breakage data I had was from the earlier spec'd ammo
Anyone ask Zak what life he is getting? However I hardly view replacing a bolt at a rate that is about twice the 5.56mm to be a deal breaker.
Well.. that means we'd be getting 1500-4000 rounds out of a 6.8 bolt, 1500 in a hard-run gun. I'm all for PMCS, but a gun that may have a bolt failure after 1500 rounds is unsat, in my book. Especially when I can get 80% of the 6.8's performance out of MK262 in a properly set up gun.
piss poor cost:benefit ration for me but Ymmv.
One of the lugs broke on my Model 1 Sales bolt at around 5000 rounds last month. That's pretty good for a bottom-of-the-line part. Coincidentally, I rebuilt the upper with a 16" Noveske barrel and CMT parts a couple of weeks ago. We'll see how long the bolt lasts this time. I bet I get to 10,000 rounds this time (if I can afford it...).
Stephen
(if I can afford it...).
I think that will be 99.99% of civilian issues rather than breaking a bolt.
The reason that I went with 6.8 is because I wanted a harder hitting cartridge out of a 10.5" barrel. I had serious issues with 5.56 out of that length barrel in Iraq using M855. So my choices were to shoot Mk262 and get about 100-120 yards of fragmentation range (depending on who you ask, I have my own doubts), or go with 6.5 Grendel or 6.8 SPC and do my own research to find it's performance data. Based on ammo costs, all three rounds (Mk262, 6.5G, and 6.8SPC) were all about the same, but based on initial research, both the 6.5G and the 6.8SPC would outperform the bigger 5.56. So, the choices were 6.8SPC or 6.5G. The reason that I chose 6.8 over the 6.5 is because of two reasons:
1. 6.8 uses a stronger bolt than the Grendel
2. 6.8 is produced by more than one company (competition is good)
The 5.56 would be a good idea for a limited budget as you could just buy military surplus ammo to practice with and then buy some heavy rounds for SHTF.
Through the testing that I've done, I've only shot around 1,000 -1,200 rounds of various manufacture, so I can't tell you about bolt failure....yet.The longest shot that I have taken was 225 yards, but the SSA SMK round fragmented like crazy at that range, so I'm surely happy with the terminal ballistics. I haven't had much more time to do further research, but I think that the Hornady loaded V-max would have much more frag range than that. As far as accuracy goes, I consistently will go sub MOA with SSA SMK's and close to it with Hornady V-max's. I'm very happy with the round and encourage you to try it if it will fit your needs, however it's not for everyone.
Grendelizer
10-03-06, 17:34
1. 6.8 uses a stronger bolt than the Grendel.
Shark, you probably just misworded this and didn't mean to make such an unsupported and erroneous statement, as it would first appear. You probably meant to say that you're guessing the 6.8 bolt is "stronger" because its case head diameter is slightly smaller than 65G's.
Unless you meant it exactly the way you wrote it? In which case I think it would only be fair to present some sort of technical-level proof to back up that statement.
Having said that, Alexander Arms' Beowulf and Grendel bolts (the same unit is used for both) are not your run-of-the-mill 7.62x39 bolt, but have certain engineering details in materials and design that improve their function with those cartridges.
John
Shark, you probably just misworded this and didn't mean to make such an unsupported and erroneous statement, as it would first appear. You probably meant to say that you're guessing the 6.8 bolt is "stronger" because its case head diameter is slightly smaller than 65G's.
Unless you meant it exactly the way you wrote it? In which case I think it would only be fair to present some sort of technical-level proof to back up that statement.
Having said that, Alexander Arms' Beowulf and Grendel bolts (the same unit is used for both) are not your run-of-the-mill 7.62x39 bolt, but have certain engineering details in materials and design that improve their function with those cartridges.
John
Roger that, I meant that the boltface had more material on it than the Grendel Boltface, and that if the two bolts were made out of the same material or had whatever designs to improve durability built into them that the 6.8 bolt would always be stronger due to the extra material, was I wrong? What features are you talking about? I wasn't meaning to bash the Grendel, far from it, and in another thread about 6.8 I mentioned that the Grendel is certaintly the way to go if you need a long distance cartridge to shoot an AR at long distance. Hell, I'll probably buy a 24" upper if wolf ever gets it's ammo to the market. But I do think that the cartridges are not for everybody and neither is a fix-all-do-all cartridge. But based on my needs, I felt that the 6.8 would serve me better. I was just responding to his thread about why I chose 6.8 SPC and why. If any of my information is incorrect, it won't be the first time or last time, but it made sense to me.
PS What did you do exactly to strengthen the bolt? Did you put relief cuts in the lugs like LW did to stiffen them? What material did you make them out of? Are they still compatible with 7.62x39? If they are, you and R. Knight II need to get together and sell about a million AR47's to the military:D
Bill Alexander
10-03-06, 20:42
Be very careful of what looks to be obvious when you are dealing with fatigue analysis, especially in complex geometry items like a bolt head. To try and give an example that is easier to understand, let's take two steel bars and mount them as a cantilevers with a reversing loading on the free end. One bar is now set up with a crack running 1/3 of the way through, while the other has a nice smooth semi circle cut out of it to a depth of 1/3, the same as the crack. The bar with the semi circle of material removed has significantly less material left in it, so which one is going to fail first.
If I might offer appologies at this stage, I am not going to profer the design details of my bolts over the internet, and you must sympathize with me that I find more than a little amusement in seeing the discusion of the 6.8 suffering from simple but critical design oversights Suffice to say the Beowulf/Grendel bolt design has proven itself historically in close to 9000 units over a 5 nearly 6 year time period. While some are low round count units I also have fielded units where the usage rate will rapidly exceed what is expected from a normal weapon.
I think this thread is not an appropriate place to enter a 6.? discussion, especially as this subject has been somewhat beaten to death. The original question was "Why did, or will you choose the 6.8"
Bill Alexander
Be very careful of what looks to be obvious when you are dealing with fatigue analysis, especially in complex geometry items like a bolt head. To try and give an example that is easier to understand, let's take two steel bars and mount them as a cantilevers with a reversing loading on the free end. One bar is now set up with a crack running 1/3 of the way through, while the other has a nice smooth semi circle cut out of it to a depth of 1/3, the same as the crack. The bar with the semi circle of material removed has significantly less material left in it, so which one is going to fail first.
If I might offer appologies at this stage, I am not going to profer the design details of my bolts over the internet, and you must sympathize with me that I find more than a little amusement in seeing the discusion of the 6.8 suffering from simple but critical design oversights Suffice to say the Beowulf/Grendel bolt design has proven itself historically in close to 9000 units over a 5 nearly 6 year time period. While some are low round count units I also have fielded units where the usage rate will rapidly exceed what is expected from a normal weapon.
I think this thread is not an appropriate place to enter a 6.? discussion, especially as this subject has been somewhat beaten to death. The original question was "Why did, or will you choose the 6.8"
Bill Alexander
I agree and I was just explaining why I went with 6.8, I only mentioned the 6.5 to explain my thought process. I thought that I had a legitimate point on the bolt issue, but I guess that you made relief cuts in the lugs or something else to strengthen them unless you made them out of some sort of unobtanium:D . LW tried to address the issue with their 6.8 bolts by making strengthening cuts and I've recieved mixed feedback on them in regards to their extractors, so the jury is still out for me on the bolt issue and I'll stick with PRI bolts for now. I don't understand why you wouldn't disclose what was done to strengthen the bolt, as anyone with an AA rifle could just pop it open and take a picture of it to shed more light on the subject, I mean how could it really be that secret? I am very interested in a 20-24 inch Grendel upper and it may be in my near future, as I think that the 6.5 is a frickin' bad ass long distance cartridge, but would like to know more about the bolt. While I realize comparing a 10.5" barrel to a 24" barrel is a apples to broccoli comparison, I think the two cartridges are just as dissimilar to each other. While the argument of which is better could last for days, I think that two points could be made without question:
1. In an extremely short 10.5-12.0 inch barreled CQB gun, the 6.8 would probably serve you best in that rifle's designed use of 100-200yds.
2. In a full size 20-24 inch barreled sniper or DMR rifle, the 6.5 would win hands down past 100yds.
I won't touch the debate about any other barrel lengths as I don't think that this is the place and it has been hashed out elsewhere, the point of this post is to clarify what I posted earlier in that neither will serve the best in every role and that the original poster should consider what type of platform serves his needs best. At either extreme the answer is obvious and pretty much undebated. I thought that if the guy was looking for a long distance shooter that there was a better option for him that he should know about before committing to the 6.8SPC as the velocity gains from a 16" to 20" SPC barrel are about 50fps.
Mr. Alexander I promise you that I hold you and your design in the highest regards and by no means am I questioning either. But I really would like to know more about your bolt and if you have plans on selling them seperately. Sorry if I came across the wrong way.
Another reason that I went with 6.8 that I didn't mention was that the increased bore size would give the powder more space to burn, thus increasing efficiency out of a 10.5" barrel.
I think this would be a good time to interject our one main focus here at M4Carbine.net:
We want to deal with accurate information. Not suppositions. Not guesses. Not hypothesis creation for the sake of disparaging gear we didn't choose to buy.
In short, if you have firsthand knowledge of a problem. We would love to hear about it.
If you are quoting material that is EASILY backed up by sources who are credible, for the sake of furthering a discussion, we welcome it.
If you are going to post unsubstantiated opinions, they should NEVER create a reason for someone like Bill Alexander, John Noveske, Mark LaRue, or anyone else to have to come here and defend their products or designs.
We all have opinions on gear, and some of them are backed up by real data. Some are not. We are not going to deal with the ones that aren't.:)
"Strengthened" 6.8 bolt for those interested in what exactly has been attempted to strengthen a bolt in the past by others. I believe that they use a different material as well versus a standard AR bolt.
http://i104.photobucket.com/albums/m182/shark31/acb.jpg
"Strengthened" 6.8 bolt for those interested in what exactly has been attempted to strengthen a bolt in the past by others. I believe that they use a different material as well versus a standard AR bolt.
http://i104.photobucket.com/albums/m182/shark31/acb.jpg
The bolt design you see there was spec'ed for use in the Leitner-Wise .499. Which had suffered from accordian bolts, lug shearing, and other bolt maladies.
They carried over the design features to their 6.8SPC and 5.56N bolts.
I am nearly certain, 99.8%, that design was not brought to market for the 6.8SPC.
"Strengthened" 6.8 bolt for those interested in what exactly has been attempted to strengthen a bolt in the past by others. I believe that they use a different material as well versus a standard AR bolt.
http://i104.photobucket.com/albums/m182/shark31/acb.jpg
Based on nothing more than reading a few problem threads on another forum................ It seems to have "Issues".
It has be hyped to all hell, but as for being "Advanced" the jury is still out.
I think this would be a good time to interject our one main focus here at M4Carbine.net:
If you are going to post unsubstantiated opinions, they should NEVER create a reason for someone like Bill Alexander, John Noveske, Mark LaRue, or anyone else to have to come here and defend their products or designs.
We all have opinions on gear, and some of them are backed up by real data. Some are not. We are not going to deal with the ones that aren't.:)
I tried to backup what I said with proof that if you wanted an "enhanced" 6.8 bolt that they were out there as Mr. Alexander said that it was a design flaw he found amusing, and I believe that LMT is working on one for their MRP barrels. The fact is that some of us choose to stay as standard as possible with AR parts as many enhanced products end up being not too terribly advanced. I showed an example for my argument, but yet I get chastised for making claims not backed up by real data when Mr. Alexander makes a reference to steel bars and then says he won't disclose any of his design details regarding to his bolt design. Now who's making voodoo magic claims?
I already said that there were reliability (extractor issues, not strength issues) issues with that bolt, which is why I went with a MP tested PRI bolt. I was just told by Grendolizer that I was making unfounded claims about bolts and wanted to clarify that they weren't unfounded. I believe that you are correct that the design branched from the .499 project, however it is touted as to having several features that would make it stronger and is 6.8 specific. The reliability issues with this design are why I wanted to know more about what Mr. Alexander had done to his bolts to make them "stronger". LW and LMT went into great detail about what they did to "enhance" their new bolt designs so that people could understand what they were buying before they dropped their coin, and I find it difficult to understand why you wouldn't disclose such a thing to the market.
So I don't think that me stating that if the two bolts were designed with the same strengthening features as well out of the same material that the bolt with a thinner bolt face would be inherently weaker. If Mr. Alexander chooses to not disclose what he has done to "enhance" his bolt, then are we just supposed to say "It's stronger than the 6.8 bolt because Bill Alexander says so"? I am not trying to start a 6.? debate, far from it I even reccomended 6.5G to the original poster if it fit his needs, but I don't like people saying that my statements are unfounded and then offer no material to rebuke it. If it's stronger show me how so that myself and others can make their own decisions and maybe buy some of your products with some kind of knowledge about what we are spending our money on.:D
As far as I'm concerned Knights is the only manufacturer to ever make an enhanced bolt. The rest are just pretty pieces to spend extra money on.
<<SNIP>>
What you did is make a claim that the 6.5G bolt was weaker than the 6.8SPC bolt.
Now prove it. If you can not, then the supposition is unacceptable.
We will not have industry professionals, manufacturers or dealers having to defend thier designs to accusatory, or errant posting. You are trying to convey YOUR opinion as a statement of fact and placing the responsibility on others to prove your unsubstantiated rumors incorrect. That is unacceptable.
Also, I see that you are now acutely accusing Bill Alexander of "voodoo magic claims". I believe the site owner's are very serious about culling this type of post/poster/
If you need to discuss the matter further, IM me. If my explanation above needs clarification please contact a staff member.
Roger that, I meant that the boltface had more material on it than the Grendel Boltface, and that if the two bolts were made out of the same material or had whatever designs to improve durability built into them that the 6.8 bolt would always be stronger due to the extra material, was I wrong? What features are you talking about?
I clarified my statement further by saying this in my second post responding to the Grendolizer. I didn't get an answer. He said that the bolt had been made out of better materials and had strengthening features built into the design to improve strength and that the 6.8 didn't which was a design flaw. That was incorrect as I pointed out that at least one company had made production "enhanced strength lifetime bolts".
Myself and many others think along the lines of what Nitrox just stated:
There just isn't a good "enhanced" bolt, they all have bugs it seems. These people would run as standard of a bolt as possible which would leave my previous post as correct if the laws of physics still apply at M4carbine.net. If some kind of "proof" is needed to as to how tough they are here's what LW have to say about it:
"Some info on the Advanced Combat Bolt. The ACB is the result of a systematic front to back dynamic analysis of the standard bolt. Nothing is there that doesn't need to be; it's designed and engineered to outlast the host weapon. It is being evaluated by a number of government and commercial enterprises. The steel is actually EN36 BS970 655M13 or 3312 AISI/SAE. It's a nickel chromium case hardening steel. It gives a very hard surface with a strong core and retains a high degree of toughness. There is enough nickel in the steel to give it the same corrosion resistant properties as stainless steel. This still is primarily used in the manufacture of gearing for mining equipment that comes under great sudden load much like an M4 bolt does. Please note the lugs have proper stress releif I beam cuts. These do just that, relieve the lugs of metallurgic stress and thus preventing fractures forming. They also decrease the bolt face mass reducing unlock time.
When you get the technical drawing for the M4 bolt, you note there are tolerences on it. These tolerences are an acceptable range in which the dimension can measure and still be acceptable from a QI perspective. Some tolerences are extremely critical on the lugs as they can effect headspace. These bolts are held to a much tighter tolerence range as LW wanted the lugs to be run to maximum dimension for strength and integrity as well as very consistent headspace lockup. What we have found are some accurracy benefits with the ACB that would equate to running a tight or match chamber without the disadvantage of the decrease in reliable extraction related to a tight chamber. So out of a standard 5.56 Nato chamber, we are getting results similar to a match chamber. Of course there are other factors involved making a match chamber accurate, and this bolt only addresses one of these, but the biggest seems to be consistent headspace lock up from round to round.
Note the dual extractor spring extractor. Both springs are widened at the base so they are captured in the bolt. The springs themselves are rated for millions of cycles. The springs both contain synthetic buffers eliminating extractor bounce or skip. "
Now that sounds kinda like the "proof" that you were talking about. Fact is I don't want to run anything like that in my rifle, I like it to be as true to the original design as possible. Now maybe I'll try one out down the road and I guess that I'll have to when I run a 6.5 G, but I just don't drink that Kool-Aid right now, but at least I know why LW thinks that their product is worth a damn, because they tell you why, and don't just treat people like they don't understand physics.
I didn't mean to get into a 6.? debate, certaintly not with a sponser of this site. I also however don't enjoy being treated like an ingnorant child. I told the poster why I chose 6.8 because that was what the thread purpose was. I stated also that either cartridge should be considered if one wished to change to a bigger caliber. While both will serve you well as a replacement for 5.56 both will have tradeoffs in reliablity off the bat, these tradeoffs will make one caliber choice better suited to your intended purpose. BUT YOU SHOULD LOOK AT BOTH IF YOUR CONSIDERING EITHER.
6.8 has smaller capacity standard sized magazines as well as some very expensive magazines, had a batch of bad ammo/chamber spec problems caused by one type of cartridge by one company, and loses it's legs fairly quickly with the current downgraded ammo. Those are some issues with the 6.8 SPC that you should consider as well. You also have issues with the Grendel, it's proprietary so ammo and rifles parts (recievers, bolts, barrel extensions) are stuck with those companies supply chains, it has a smaller bore with less effeciency out of extremely short barrels, as well as the afformentioned bolt issue.
I will state this as opinion so that I will not get flamed or offend anyone:
1. If I was going to build a more capable SBR (10-12.5") I would go with 6.8 because of the larger bore size and greater efficiency and greater energy from the muzzle where most of my intended targets with this rifle will be close to. Also I want to run a "standard" MP tested bolt and bolt group as I believe it's the most reliable, so due to the extreme forces involved with the gas system on these rifles, using a thicker bolt face on a standard bolt leads me back to the 6.8. The bottom line with these size rifles is that if you shoot them enough, have spare parts (I haven't broken anything yet, but have spares ready and onboard the rifle:D )
2. If I was going with a carbine (14.5-16) I would stick with a 5.56 and be fine with it. If you have the need because of hunting restrictions in your area, want to build an effective "Recce", or just a hankering to blow up your target and you had to use 6.? and this is your preffered barrel length, you need to look at the hard facts of both cartridges lined out above. One WILL fit your needs more than the other, just decide what your needs are.
3. If I was going to go over 16", it would be silly to go with the 6.8 for the simple fact that you don't get squat for return on the extra barrel length somewhere in the 'hood of 50FPS. To me the purpose of a 6.? with a barrel over 16" is to reach out there and knock the crap out of something at a pretty good distance. The Grendel has found it's home in an SPR type rifle, it outperforms 6.8, 5.56, 7.62x39, or anything else you care to run through an AR15 at intermediate ranges. While I would preffer a larger cross section to hit my target, I feel this is THE way to go if you need to go past 600M hands down. Also I would worry less about parts breaking on a precision rifle as I will hopefully be far far away when it happens. I will buy one eventually when funds allow.:D
I can't think of anything else to say, If I don't know your intended purpose, then I can't make a real recommendation, but my above opinions should apply. I have pissed off too many people but I feel as though the poster should be more educated now than he was before. I have given my two shiny red pennys on the subject and will now promptly shut up before I anger the mods or sponsers any further.
Bill Alexander
10-05-06, 21:19
Let's play bolts!:D
First I am going to let you know that you have been royally screwed with your "PRI" MP bolt. The manufacturer (Not PRI) of that item is also making them for near everyone else, they are bought under sub contact and are actually quite a good bolt. In the absence of a standardised loading outside of the current CIP approval and the consequential absence of of a calibrated HP round (discussed on this forum) please illustrate what possible use magnetic particle inspection of the bolt has. In the absence of the overload condition, MP simply indicates that the bolt is made out of a magnetic ferrous base and that it has some internal corner radii. If that core is now running at +48 HVN you will not know (you will find out rather quickly when it is in the gun) nor will you know if you have geater than 10% carbide stringing on the grain boundries, if the case hardening extends to the correct depth or if the defusion during tempering has overhardened any of the thin critical sections. What you have paid for is a test report that says that the item is not cracked prior to recieving any loading whatsoever. Could just be a good cast iron piece at this stage. Maybe you should not believe something just because someone says so?
So what are the flaws that amuse me so? Well just for starters there is no standardization of the chamber or working pressures. In this absence the bolts are simply cut out versions of the plain 223 commercial offerings. Look at that minor diameter under the lugs, notice something, its a 223 bolt. No work at the base of the extractor groove, standard rad at the back of the lugs, no geometry changes in the bolt face except the diameter and the same material. Good stock stuff for a 223, probably about as cheap as you dare make it without having liability issues. Now let's add a bigger cartridge running at higher pressures. No pressure loads, heat treat from the old .mil prints for the M16 and no one specifying a micrograph standard for structure or the core properties at defined points in the cross section. No disrepect to the company making these things, I could do little better if the whole design brief simply consisted of let's cut a bigger case recess.
It would appear that the very simple illustration of fatigue design was not adequate so I will assume that your background in metallurgy, strain energy/shear energy analysis and fatigue calculation is non existant. In this light let us now look at the bolts from LMT and LW. Karl Lewis is a comenserate designer and is both innovative and skilled. In the work on the LMT bolt (we will ignore the very clever extractor for now) he was specifically addressing the bolt life requirements for the enhanced M4 and had to live with those parameters. The thrust loading imposed on that unit is suprisingly exactly the same as that from the M16 but the timing created a more complex stress in the lugs which can and does fail the two lugs either side of the extractor groove. This is the result of uneven loading from high spots and imposed bending stresses The very visible feature of the LMT bolt is the grooving about the major diameter of the lugs. Note how small this groove is and its position reference to the loaded surface. The design very carefully equalises the stresses imposed on each lug without increasing the compressional loading on the material in contact with the barrel extension. So far the bolt is actually no stronger than a conventional design, just a BIT more flexible. The smart bit that adds strength is the little details. Some you can see such as the radius at the rear of the lugs Close inspection shows that this actually undercuts the bolt body ( See illustration with bar above), some you probably cannot see even though it is straight in front of you. There are an additional two features within the LMT lugs as physical geometry that actually enhance the fatigue life of the bolt. (Name both and describe the mechanism and I will sell you a Grendel of your choosing at factory cost (Karl may not apply)). The last part of the LMT bolt is that the material is indeed different. The specific alloy is selected for its resistance to fatigue loading. This alloy and heat treatment is specific to LMT and I will not give details. Suffice to say I am very impressed.
Turning quickly to the LW bolt, I will assume that you are citing this as a design that enhances the strength. Ooo! look it has a groove about the lugs, it must be stronger! If you have read the above and have studied the LMT design you might just notice that the back of the lugs might now increase the contact stress on the material rather than sharing it. Much as I hate PLW I will not indulge in assasinating the design which now rests with a company that is vocally not associated with him. I have read a great deal about 3312 "stainless steel" alloy that increases the strength. Here is a hint; that alloy is not stainless, and it does not appear on the list of alloys that do well in cold enviroments, here's another hint it was ditched for making 1903's
So finally we get to the Grendel/Beowulf bolts. In the first instance I select an alloy that is well suited to the design. Good fatigue life, very desirable micro structure, and then I define a certified heat treatment route with built in tolerances for the structure and properties so that even if we get to the edges of the tempering or cryogenic treatments the result still falls firmly into specification. Lugs get the maximum allowable radius at the rear and we adjust the little features that you named from the LMT discussion to add strength. Remember that little bit of flex needed to equalize the stress at the contact points without allowing too much movement to increase contact loads. This is where the design must be considered as a whole. With the correct material and recess diameter I can now get the spring needed from the bolt without adding grooves to the top of the lugs. But the absence of grooves must still make it crap! because that is what you were told they do on the internet.
You are wading out into some very complex waters. I am going to tell you that I reverse the sequence of the temper and cryo at the end of the heat treatment for the alloy I use, as the retained austenite in the material is stable and the dimesional gains from this reversal outweigh anything I can get from the properties. Can you ellaborate on this descision and let me know your thoughts about the effect of peening and phosphating on the finished part. Even if I laid bare the alloy, heat treatment, geometry and process drawings could you really form an educated conclusion about the strength of the bolt.
I make my living being able to design and sell the stuff that other people cannot get to work. I have over seventeen years of experience in the field of weapons design, many of these as lead engineer on equipment that you might just see as a rumour in the next 10 years. I carry a security classification that you need to be cleared for just to find out what the level is, but I cannot educate you in materials science and fatigue analysis in a forum on the internet. I really do not care either way if you believe me or not, but it would be nice to have you trust my integrity that I will not sell a sub standard or badly designed weapon. As long as I head engineering at AA we build each rifle like it is the one I will buy myself, no seperate line for mil and civ orders and absolutely everything has to be safe.
Bill Alexander
Yeah!
...because Bill Alexander said so. ;)
Bill thank you for responding, and giving insight into your design process.
I appreciate you taking the time to answer the questions posed.
shark31, you are 100% entitled to YOUR OPINION. M4C wants members to share their FIRST hand knowledge on gear (not something they read on another site). It appear that many of the things you have stated about the 6.5 has been taken from internet rumor (not first person).
Trade secrets are just that (secret) and if a manufacturer doesn't want to spill the beans on one of their designs then so be it. The companies that have been invited to sponsor M4C were picked for their high quality CS and their ethical busines practices. Their word should be consider golden until PROVEN other wise.
Bill Alexander
10-05-06, 21:58
Sorry, I write slowly and spent so much time writing that I have just caught up with the last few posts.
Shivan. Please do not be too hard on Shark31. This industry is full of people who say they have the greatest design in the universe ever, then you spend those hard earned dollars and get a gun that groups like a shot shell on the five occasions that you manage to unjam it, just before it breaks and you find that the company never answers its phones and does not accept liability for any defects whatsoever. I cannot really blame him for being suspitious.
That write up from LW is rather good. Lots of alloy specs: is a back dynamic analysis sort of sketching the design as you run wildly while looking over your shoulder. I also like the bit about metallurgical stress, sounds grand, wonder why you never see the term in text books on either metallurgy or stress analysis. Anyway its got me fooled almost as well as poor old Nitrox who is conviced that KAC builds those enhanced bolts. Check the springs, if they are angled out the thing is LMT.
Bill Alexander
Myself and many others think along the lines of what Nitrox just stated:
There just isn't a good "enhanced" bolt, they all have bugs it seems. These people would run as standard of a bolt as possible which would leave my previous post as correct if the laws of physics still apply at M4carbine.net. If some kind of "proof" is needed to as to how tough they are here's what LW have to say about it:
I did not state that.
Mr. Alexander, thank you. That was more along the answer I was looking for, now I need to do more research proffessor:D . I wasn't doubting that you had a great design, and have said just that previously. I just wanted to know why, so that I could research all choices further, knowledge is never a bad thing. I still would like to run a standard bolt in my rifles, and I was told that it was tested after machining to 6.8 (I will certainly check into that soon, but it's fine so far). But now that I have your ear, could I ask one last question:
If you designed all the features that go into your bolts and designed a 6.5 as well as a 6.8 bolt, which would be stronger (If the 6.5 would be stronger, then would that also mean that the 6.5 would be stronger than the 5.56 of the same design with even more material around the casehead)? This is what I was having a hard time with.
I'll also have to get back to you on the LMT bolt quiz, I may get to do my terminal ballistics testing sooner rather than later with the Grendel, what round do you recommend for deer pest control where I can't harvest any meat:D ? The only problem is that I've always seen enhanced bolts as a gimmick and Haven't a clue what one actually looks like.
Please accept my apology if you felt attacked, this forum is a great place in that consumers can get answers directly from the horses' mouth as has just been demonstrated, and I don't want to abuse it. I just didn't like being told "because I say so" in a technical forum, it sounded like hype, which is what I wanted the original poster to beware of, sorry. I just REALLY think that the guys that push either one for EVERY PURPOSE UNDER THE SUN are completely full of crap, they each have their limits.
Anyway its got me fooled almost as well as poor old Nitrox who is conviced that KAC builds those enhanced bolts. Check the springs, if they are angled out the thing is LMT.
Bill Alexander
Bill,
Please go back a rearead what I wrote, I made no mention of sub contractors. Knights designed the bolt and it is structural advancement, enough said.
As far as I'm concerned Knights is the only manufacturer to ever make an enhanced bolt. The rest are just pretty pieces to spend extra money on.
I know, you said this. I didn't quote you as people could read it themselves.
I want a 6.8 because it's big enough to kill whitetail with.
Shot one for the first time today. Liked it. Liked the SF suppressor on the other rifle too. I will definitely have to get a SF 6.8 can.
Robb Jensen
10-06-06, 04:04
Paul, is that you?
Nitrox,
This is counter productive, and a violation of rule # 6 (Trolling – Posting comments with the purpose to start conflicts with members, libel persons or groups, or to disrupt the overall running of the forum will not be allowed.) if you can't have the utmost respect for others here you can leave this site. Consider this a final warning.
Robb
I want a 6.8 because it's big enough to kill whitetail with.
Shot one for the first time today. Liked it. Liked the SF suppressor on the other rifle too. I will definitely have to get a SF 6.8 can.
AA is working with Gemtech on a can and if you want something that is flatter shooting and packs more punch at much longer ranges, then you need to look at the 6.5.
C4
AA is working with Gemtech on a can...
Or if you really wanted to, you could get a Gemtech HVT in .30 and probably be as quiet.
I considered the Gemtech HVT, but got a killer deal on 2 YHM .30 cal suppressors. One will go on the Grendel I built and one on the AR-10. :cool:
Or if you really wanted to, you could get a Gemtech HVT in .30 and probably be as quiet.
I considered the Gemtech HVT, but got a killer deal on 2 YHM .30 cal suppressors. One will go on the Grendel I built and one on the AR-10. :cool:
Roger. Wait till you see the 6.5's I am going to build, you will want to sell the one you have. :D
C4
If you designed all the features that go into your bolts and designed a 6.5 as well as a 6.8 bolt, which would be stronger (If the 6.5 would be stronger, then would that also mean that the 6.5 would be stronger than the 5.56 of the same design with even more material around the casehead)? This is what I was having a hard time with.
I guess the fundamental problem with your question is that it has no relevance as to whether AA 6.5 Grendels have a longer bolt life than any particular manufacturer's 6.8 rifles (which is the question you are probably trying to ask).
The nice thing about the Grendel when compared to the 6.8 SPC is that you *know* that Gendel ammo, bolts, chambers are all designed to be compatable with each other. There is one set of specs controlled by one entity so you don't have to worry about whether a bolt from manufacturer A can handle the bolt thrust genereated by ammo from manufacturer B fired in a chamber from manufacturer C...
I guess the fundamental problem with your question is that it has no relevance as to whether AA 6.5 Grendels have a longer bolt life than any particular manufacturer's 6.8 rifles (which is the question you are probably trying to ask).
The nice thing about the Grendel when compared to the 6.8 SPC is that you *know* that Gendel ammo, bolts, chambers are all designed to be compatable with each other. There is one set of specs controlled by one entity so you don't have to worry about whether a bolt from manufacturer A can handle the bolt thrust genereated by ammo from manufacturer B fired in a chamber from manufacturer C...
Agree. A lot people snub their nose at how AA controls ammo, chambers, etc, but when it comes right down to it, this is a good thing and helps to keep QC very high.
C4
Agree. A lot people snub their nose at how AA controls ammo, chambers, etc, but when it comes right down to it, this is a good thing and helps to keep QC very high.
C4
Unless you're Shivan... ;)
Stephen
Agree. A lot people snub their nose at how AA controls ammo, chambers, etc, but when it comes right down to it, this is a good thing and helps to keep QC very high.
C4
Yes, it's hard to have QC problems on Ammo, reloading components, and Dies when they don't exist.
I know that's a bit harsh, but I'm kinda grumpy about this subject at the moment. I waited a long time before finally buying into the Grendel thing (Which I do think is the best choice for my use), waiting till I thought it was a viable product with good supply. All the reports I had been reading were good. Imaging my disappointment after receiving most of the parts I needed (minus the Larue receiver) and not being able to find anything to shoot from the damn thing once it's built. No ammo (maybe a month to two months), no brass (Finally found some once fired brass), and no reloading dies.
When you look at the ballistics of the two, 6.8mm SPC and 6.5mm Grendel, it should be obvious to anybody that the Grendel beats the SPC out past 300m or so. There's no question that apples to apples the Grendel excels at longer ranges. The thing to consider is for what purpose you will be using the cartridge. I don't have access to a range farther than 200 meters and if I ever used one of my rifles for self defense purposes I'd be hard pressed in finding an excuse for shooting someone outside of 300m (10 to 25 meters is much more realistic). That being the case I chose the availability of parts and factory loaded ammo (though not initially). It didn't hurt that I knew Steve Holland personally through mutual friends at Lightfighter.com and got to see the progression of the cartridge and shoot it early on while I was stationed at Ft Campbell. The 6.8mm SPC is a very accurate cartridge inside it's performance envelope and it's just a hell of a lot of fun to shoot. Ammo is down to about .50 cents a round for plinking and if you reload you can get it down in the .30 or .40 cent range by reusing your brass.
Either cartridge is a fine choice for what 99% of hobby shooters will use them for; deer hunting or shooting paper targets at the 100 yard public range.
Stephen
Unless you're Shivan... ;)
Whoa there....it looks like you are kidding....but I am perfectly fine with Bill's methodology.
I am not thrilled with the lead times on getting the stuff.
They are connected, but independent. :)
Whoa there....it looks like you are kidding....but I am perfectly fine with Bill's methodology.
I am not thrilled with the lead times on getting the stuff.
They are connected, but independent. :)
Just poking a little fun. The "SPC" crowd took a lot of shit from the "Grendel" crowd about ammo supplies that first year. Sorry to have some fun at your expense:D
Stephen
Yes, it's hard to have QC problems on Ammo, reloading components, and Dies when they don't exist.
I know that's a bit harsh, but I'm kinda grumpy about this subject at the moment. I waited a long time before finally buying into the Grendel thing (Which I do think is the best choice for my use), waiting till I thought it was a viable product with good supply. All the reports I had been reading were good. Imaging my disappointment after receiving most of the parts I needed (minus the Larue receiver) and not being able to find anything to shoot from the damn thing once it's built. No ammo (maybe a month to two months), no brass (Finally found some once fired brass), and no reloading dies.
Understand. I think the ammo situation will be resolved when Wolf comes on line. They will be bringing 3 new 6.5 rounds (two high end, brass models and one steel cased round).
C4
When you look at the ballistics of the two, 6.8mm SPC and 6.5mm Grendel, it should be obvious to anybody that the Grendel beats the SPC out past 300m or so. There's no question that apples to apples the Grendel excels at longer ranges. The thing to consider is for what purpose you will be using the cartridge. I don't have access to a range farther than 200 meters and if I ever used one of my rifles for self defense purposes I'd be hard pressed in finding an excuse for shooting someone outside of 300m (10 to 25 meters is much more realistic). That being the case I chose the availability of parts and factory loaded ammo (though not initially). It didn't hurt that I knew Steve Holland personally through mutual friends at Lightfighter.com and got to see the progression of the cartridge and shoot it early on while I was stationed at Ft Campbell. The 6.8mm SPC is a very accurate cartridge inside it's performance envelope and it's just a hell of a lot of fun to shoot. Ammo is down to about .50 cents a round for plinking and if you reload you can get it down in the .30 or .40 cent range by reusing your brass.
Either cartridge is a fine choice for what 99% of hobby shooters will use them for; deer hunting or shooting paper targets at the 100 yard public range.
Stephen
It is important to pick the right tool for the job. I do think the 6.5 will do just fine in CQB environment and plan on making on 10.5's.
I have a round that will do pretty well out to 300m. It is called the 5.56. I want a weapon that can reach out and touch someone past 600M with authority.
I think the problem with the 6.8 is that a lot of companies don't know how to load the cartridge (too hot or too weak) and a lot of companies seem to vary on chambers (which is why we see all the blown primers). The consistancy just isn't there IMHO and is why I have stayed away from the 6.8 to date.
C4
Just poking a little fun. The "SPC" crowd took a lot of shit from the "Grendel" crowd about ammo supplies that first year. Sorry to have some fun at your expense:D
Stephen
And the 6.8 crowd (cough HFG cough) has TOTALLY screwed AA over on several forums. What goes around, comes around.
C4
It is important to pick the right tool for the job. I do think the 6.5 will do just fine in CQB environment and plan on making on 10.5's.
Agreed.
I think the problem with the 6.8 is that a lot of companies don't know how to load the cartridge (too hot or too weak) and a lot of companies seem to vary on chambers (which is why we see all the blown primers). The consistancy just isn't there IMHO and is why I have stayed away from the 6.8 to date.
C4
I don't think it's a problem with the ammo companies, there's only such much you can do with a 30 grain case capacity. That and Remington initially quoted 2850 fps but that was from a 24" barrel and knowbody wants to lug that around. Chop 8" off and you get down to 2550-2600 fps which seems to be the velocity that everyone's delivering.
I have a round that will do pretty well out to 300m. It is called the 5.56.
I don't want a round that does "pretty well" out to 300m. I want a cartridge that freakin' OWNS the 0 to 300m shots in a compact carbine package. That is where 99% of rifle engagements take place. That is handily accomplished by the 6.8mm. If 6.8mm SPC ammo were just a little cheaper I wouldn't have any 5.56mm guns.
Stephen
I don't want a round that does "pretty well" out to 300m. I want a cartridge that freakin' OWNS the 0 to 300m shots in a compact carbine package. That is where 99% of rifle engagements take place. That is handily accomplished by the 6.8mm. If 6.8mm SPC ammo were just a little cheaper I wouldn't have any 5.56mm guns.
Stephen
I hate to tell you, but the 6.8 doesn't "own" anything out to 300m. As you know, there is no magic bullet out there and the only round I would say that owns from 0-300M would be a .50 or a tomahawk. :D
C4
If you designed all the features that go into your bolts and designed a 6.5 as well as a 6.8 bolt, which would be stronger (If the 6.5 would be stronger, then would that also mean that the 6.5 would be stronger than the 5.56 of the same design with even more material around the casehead)? This is what I was having a hard time with.
So noone wants to answer this? This is what I meant in my original post and what I specifically asked in my second post to clarify. I understand that Mr. Alexander thinks that his bolt is stronger because of his improvements, but my point was that the smaller casehead provides more material to work with. There are "strengthened" bolts made for the 6.8, and I will shoot one this weekend and give a range report with video, but only plan on running about 500 rounds through it.
My point is that simple, and I think that the answer is that obvious. Mr. Alexander may have a bolt right now that IS stronger than any 6.8 bolt on the market right now, but given the 6.8's smaller casehead, and the fact that more than 1 company is working on the 6.8 lead me to believe that what I posted was correct:
The 6.8 has an inherently stronger bolt because of the smaller casehead, and if all bolts were created equal (6.5 and 6.8) the 6.8 will be stronger. To further illustrate my point, and make an apples to apples comparison, look at my inferior reamed out PRI 6.8 bolt and compare it to a 7.62x39 bolt, which will fail first?
You see, that was the point that I was trying to make, next time I make the point I will be sure to say:
The 6.8 has a smaller casehead, so more material can be used to strengthen the bolt.
Also, on the chamber issues: SSA designed the Xtreme which at first was designed with a longer throat to accomodate the projectile. Some rifles were rechambered to shoot this round and that is what caused all the fuss. Since then Art has redesigned the Xtreme and it uses the same old chamber. If you don't want to shoot the old version of that round, then you have no chamber issues with 6.8. All other SSA rounds are to spec as is Remington and Hornady offerings.
This part is my opinion, so don't flame me for this:
Mr. Alexander's bolt is probably just a durable as he claims, I don't doubt that, but I'm sure that LW or LMT could make plenty of arguments for their enhanced bolts as well. I would still call it opinion as I haven't seen test results that included both designs shot to bolt failure. LW says that they will warranty their bolts for the life of the weapon system, so I'm sure that in their own opinion they would say that their bolt is the strongest. That's all fine and dandy, and I'm pretty sure that you wouldn't have any broken bolts with any choice you made. But I just have a problem with everyone drinking the Kool Aid of any company. The simple fact of the matter is that the 6.5 has a larger boltface and thus less material around it to work with. I wasn't bashing the Grendel, I plan on buying one. I also own a 6.8. But I'm not running around telling everyone that either will be the end-all-be-all-most-perfect-in-every-platform rifle cartridge, I think that is ignorant and didn't want the poster to fall victim to it. They both have drawbacks, and one will fit your needs better than the other, simple as that.
phoenixtac
10-06-06, 15:51
I'm quite happy (Cough) with all of the responses so far, some, if not all of the information posted here shows (To Me) that there is still quite a lot of questions out there regarding the 6.8 SPC.
And I'll leave the 6.5 issue to Mr. Alexander, he is the authority on the cartridge, certainly not myself.
To me it just seems that there is a limit to the AR-15, over revving a cartridge in it leads to failures both in equipment, and performance.......the search continues.:D
So noone wants to answer this?
The answer is: "That's nice". If you're trying to fire a 6.8 SPC with a 6.5 Grendel bolt or vice-versa then maybe it's a meaningful observation, otherwise I don't see why anyone should care....
You do understand that these are 2 different catridges that have different pressure curves and put different loads on the their bolts, right? If you do the math and determine that the Grendel bolt is not engineered properly for it's application, then that would be a concern that should influence a buying decision. I haven't heard of an epidemic of Grendel bolts breaking, so I have no reason to doubt Bill A's engineering prowess and will happily leave the math to him.
So noone wants to answer this? This is what I meant in my original post and what I specifically asked in my second post to clarify. I understand that Mr. Alexander thinks that his bolt is stronger because of his improvements, but my point was that the smaller casehead provides more material to work with. There are "strengthened" bolts made for the 6.8, and I will shoot one this weekend and give a range report with video, but only plan on running about 500 rounds through it.
My point is that simple, and I think that the answer is that obvious. Mr. Alexander may have a bolt right now that IS stronger than any 6.8 bolt on the market right now, but given the 6.8's smaller casehead, and the fact that more than 1 company is working on the 6.8 lead me to believe that what I posted was correct:
The 6.8 has an inherently stronger bolt because of the smaller casehead, and if all bolts were created equal (6.5 and 6.8) the 6.8 will be stronger. To further illustrate my point, and make an apples to apples comparison, look at my inferior reamed out PRI 6.8 bolt and compare it to a 7.62x39 bolt, which will fail first?
You see, that was the point that I was trying to make, next time I make the point I will be sure to say:
The 6.8 has a smaller casehead, so more material can be used to strengthen the bolt.
Also, on the chamber issues: SSA designed the Xtreme which at first was designed with a longer throat to accomodate the projectile. Some rifles were rechambered to shoot this round and that is what caused all the fuss. Since then Art has redesigned the Xtreme and it uses the same old chamber. If you don't want to shoot the old version of that round, then you have no chamber issues with 6.8. All other SSA rounds are to spec as is Remington and Hornady offerings.
This part is my opinion, so don't flame me for this:
Mr. Alexander's bolt is probably just a durable as he claims, I don't doubt that, but I'm sure that LW or LMT could make plenty of arguments for their enhanced bolts as well. I would still call it opinion as I haven't seen test results that included both designs shot to bolt failure. LW says that they will warranty their bolts for the life of the weapon system, so I'm sure that in their own opinion they would say that their bolt is the strongest. That's all fine and dandy, and I'm pretty sure that you wouldn't have any broken bolts with any choice you made. But I just have a problem with everyone drinking the Kool Aid of any company. The simple fact of the matter is that the 6.5 has a larger boltface and thus less material around it to work with. I wasn't bashing the Grendel, I plan on buying one. I also own a 6.8. But I'm not running around telling everyone that either will be the end-all-be-all-most-perfect-in-every-platform rifle cartridge, I think that is ignorant and didn't want the poster to fall victim to it. They both have drawbacks, and one will fit your needs better than the other, simple as that.
I am wondering why you would tend to believe LW over what AA says? Is it because they put a bunch of words down on the "internet" that really don't mean anything and certainly won't be found in a metallurgy analysis? Let's not forget that PLW (AKA HFG) was the MASTER of BS and has left is stain on the gun world for many, many years to come.
C4
I've already said that I probably will still run my sad pathetic untested PRI bolt, I want to see when it breaks. But as far as deciding on gear based on shady business practices goes, I don't care, if it's better it's better. I also don't think that you read my post, I never stated that one was better than the other, just that the 6.8 had a smaller bolt face and thus more material to work with. I don't think that this is the place to question someones business practices, and the nice thing is that with 6.8 if you do care about your vendor's "unfair" business practices, go to the next guy developing products for the round.
I've already said that I probably wil still run my sad pathetic untested PRI bolt, I want to see when it breaks. But as far as deciding on gear based on shady business practices goes, I don't care, if it's better it's better. Also, maybe we shouldn't throw rocks in glass houses.
Your PRI bolt will most likely function fine (hard to say). You probably won't notice any issues (if there are any till about 3-5 thousand rounds).
Shady business practices is the UNDERSTATEMENT of the year! Have you been following the story?? Impersonating a SOCOM officer to help push his products??? That is just the start!
You kind of proved my point about believing what you read on the errornet with your "glass house" comment.
Edited to add: after you re-worded your post, unfair doesn't even come close. Go ask AA, POF, Colt, LMT, etc if what PLW did to their companies was just "unfair."
C4
Your PRI bolt will most likely function fine (hard to say). You probably won't notice any issues (if there are any till about 3-5 thousand rounds).
Shady business practices is the UNDERSTATEMENT of the year! Have you been following the story?? Impersonating a SOCOM officer to help push his products??? That is just the start!
You kind of proved my point about believing what you read on the errornet with your "glass house" comment.
C4
I edited out the glass house comment as I have not personally heard the facts. None of the information that I have posted has been from the error net, just the ad from LW to show that they do disclose what they did to "enhance" their bolt.
My question, and point that noone wants to respond to deals with fact. The casehead of the Grendel is larger. I don't take what AA, LMT, LW, or anyone else says as factual, they are trying to sell products. What they say may very well be true, but I was flamed for making a statement that noone has questioned in the past two pages of conveluted ramblings:
"If you designed all the features that go into your bolts and designed a 6.5 as well as a 6.8 bolt, which would be stronger (If the 6.5 would be stronger, then would that also mean that the 6.5 would be stronger than the 5.56 of the same design with even more material around the casehead)? This is what I was having a hard time with."
Now if you are saying that a bolt can be made with less material that is stronger than a standard reamed bolt, then I know and understand that. However, if you are trying to tell me that the 6.8 with a smaller casehead and more material will always be weaker, then I would venture to say you are wrong.
I edited out the glass house comment as I have not personally heard the facts. None of the information that I have posted has been from the error net, just the ad from LW to show that they do disclose what they did to "enhance" their bolt.
My question, and point that noone wants to respond to deals with fact. The casehead of the Grendel is larger. I don't take what AA, LMT, LW, or anyone else says as factual, they are trying to sell products. What they say may very well be true, but I was flamed for making a statement that noone has questioned in the past two pages of conveluted ramblings:
"If you designed all the features that go into your bolts and designed a 6.5 as well as a 6.8 bolt, which would be stronger (If the 6.5 would be stronger, then would that also mean that the 6.5 would be stronger than the 5.56 of the same design with even more material around the casehead)? This is what I was having a hard time with."
Now if you are saying that a bolt can be made with less material that is stronger than a standard reamed bolt, then I know and understand that. However, if you are trying to tell me that the 6.8 with a smaller casehead and more material will always be weaker, then I would venture to say you are wrong.
I am willing to bet that the majority of the "info" in the LW enhanced bolt "ad" is made up (as they use words that really don't even exist). :rolleyes:
As far as your question goes, I am not into Metallurgy so my response wouldn't be worth anything and won't waste anyones time.
C4
I hate to tell you, but the 6.8 doesn't "own" anything out to 300m. As you know, there is no magic bullet out there and the only round I would say that owns from 0-300M would be a .50 or a tomahawk. :D
C4
You forgot the "a compact carbine package" part. Without going up to the weight, size, and recoil of a 7.62 I'd say the 6.8mm SPC is it, but what the hell would I know about combat engagements:rolleyes:
Stephen
You forgot the "a compact carbine package" part. Without going up to the weight, size, and recoil of a 7.62 I'd say the 6.8mm SPC is it, but what the hell would I know about combat engagements:rolleyes:
Stephen
Your right, I left the "compact carbine package" comment out as it I can get a FAL, AR10, etc in a "compact package" without out adding a lot of weight.
I can build a 6.5 in 10.5 just like you can a 6.8. So I wouldn't say that a 6.8 is "it."
I build reliable weapons for folks going into harms way, but what do I know. :rolleyes:
C4
I can build a 6.5 in 10.5 just like you can a 6.8. So I wouldn't say that a 6.8 is "it."
C4
I can build a 10.5" rifle in .22 long rifle, but would it outperform 6.8? I think that was Stephen's point, he never said it wouldn't work, just that it wouldn't outperform.
Bill Alexander
10-06-06, 20:04
So noone wants to answer this? This is what I meant in my original post and what I specifically asked in my second post to clarify. I understand that Mr. Alexander thinks that his bolt is stronger because of his improvements, but my point was that the smaller casehead provides more material to work with. There are "strengthened" bolts made for the 6.8, and I will shoot one this weekend and give a range report with video, but only plan on running about 500 rounds through it.
My point is that simple, and I think that the answer is that obvious. Mr. Alexander may have a bolt right now that IS stronger than any 6.8 bolt on the market right now, but given the 6.8's smaller casehead, and the fact that more than 1 company is working on the 6.8 lead me to believe that what I posted was correct:
The 6.8 has an inherently stronger bolt because of the smaller casehead, and if all bolts were created equal (6.5 and 6.8) the 6.8 will be stronger. To further illustrate my point, and make an apples to apples comparison, look at my inferior reamed out PRI 6.8 bolt and compare it to a 7.62x39 bolt, which will fail first?
You see, that was the point that I was trying to make, next time I make the point I will be sure to say:
The 6.8 has a smaller casehead, so more material can be used to strengthen the bolt.
If you must goad for an answer I will yet again try and help. I appreciate your enthusiasm but if I might proffer an observation the phrase of your text is somewhat abrasive and you need to read the answers that are provided more carefully especially when they relate to areas where you are unfamiliar. If you are unsure of a piece of information, ask.
Your clumsily formed hypothesis as outlined above has the same misconceptions that you started with and you should if possible try and reference some material on fatigue analysis as this might help (if you are having problems finding good texts please contact me and I can make some suggestions to help you start). In the design of the bolt we are not addressing the problem of a single massive overload failure which exceeds the gross material strength, rather we are trying to resist the cumulative effects of fatigue
If you would re-read my hopefully simplistic description of the behaviour of the LMT bolt you will notice the highlighted section that summarises the function of the stress relief groove that this bolt has. This feature is specifically added to provide a slight flexability of the lugs. Or there is metal cut out because the lugs are too stiff. We are actually removing metal to get more life from the item. In the same way I balance the Grendel/Beowulf bolt but because I already have a larger case head recess I can set up the lugs to share the load effectively without having to make additional grooves.
Adding metal back into the bolt in this instance is actually detrimental to the life of the unit.
I have close to 9000 bolts in the field that can provide a back up for my design and the discussions that I am forwarding, so I am in the position to offer both theoretical background and a huge statistical database for the same that says I am right. If you wish to continue implying that the bolt is not suitable for the application you should present the data that backs this claim to this forum.
So I am going to tell you that a smaller case head and adding material back into the bolt in this particular scenario reduces the life of the bolt. Consider your foundation in metallurgy, static and dynamic stress analysis and fatigue. Now tell me I have got this wrong and that you are right.
I do not like to be called Professor.
Bill Alexander
So I am going to tell you that a smaller case head and adding material back into the bolt in this particular scenario reduces the life of the bolt. Consider your foundation in metallurgy, static and dynamic stress analysis and fatigue. Now tell me I have got this wrong and that you are right.
Shark31,
If you continue along your current path, I can assure you that your stay will be considerably shorter than you anticipated.
The question you posed, accused, supposed and hinted at has been answered above.
Do not further this discussion. If you have different points to clarify, or more useful information germane to this discussion, share them.
If you wish to continue your "assault", I'd suggest against it, and hint that maybe you should just leave this thread in peace.
Please consider this a goodwill gesture, and an attempt to salvage a valuable thread.
Thanks,
Ed
I can build a 10.5" rifle in .22 long rifle, but would it outperform 6.8? I think that was Stephen's point, he never said it wouldn't work, just that it wouldn't outperform.
Does the 6.8 do a better job than a 5.56 with MK262 in a 10.5? Maybe so. Does it do a better job than a 6.5 in 10.5? Not from any balistic data I have seen.
That was my point.
C4
C4IGrant
You ask:
”Does the 6.8 do a better job than a 5.56 with MK262 in a 10.5? Maybe so. Does it do a better job than a 6.5 in 10.5? Not from any balistic data I have seen.”
We were among the first folks to test heavy 5.56 mm loads starting back in 1989 and were the first to discuss the advantages of heavy 5.56 mm loadings for combat use. Likewise, we were the first to test 6.8 mm terminal performance and discuss the advantages it offers. Without any doubt, 6.8 mm offers superior terminal performance compared to Mk262 in any barrel length. Period. Regarding your second question, to date, everything test that I am aware of indicates that 6.8 mm appears to offer better terminal performance than 6.5 mm Grendel in barrels of 16” and under. Please advise us if you have any valid data to the contrary.
C4IGrant
You ask:
We were among the first folks to test heavy 5.56 mm loads starting back in 1989 and were the first to discuss the advantages of heavy 5.56 mm loadings for combat use. Likewise, we were the first to test 6.8 mm terminal performance and discuss the advantages it offers. Without any doubt, 6.8 mm offers superior terminal performance compared to Mk262 in any barrel length. Period. Regarding your second question, to date, everything test that I am aware of indicates that 6.8 mm appears to offer better terminal performance than 6.5 mm Grendel in barrels of 16” and under. Please advise us if you have any valid data to the contrary.
I don't have any issues believing the first part. Talking with people that are much more knowledgeable about the 6.8 and 6.5 than me, advise that the 6.5 is very capable at all distances.
I was wondering when you were going to show up Doc! Its not like you to miss a 6.8 thread. :D
C4
Gel Test review for those that have not seen it: http://www.65grendel.com/forum/showthread.php?t=840
C4
Bill Alexander
10-07-06, 09:28
We are testing the new 120 Berger projectile currently and the initial results indicate that it does rather well but really want to explore a lot more parameters before releasing the load. The Berger construction is promoting much earlier fragmentation than we have seen to date and I suspect (we have not tested this yet) that the bullet has a lower velocity threshold for fragmentation. This is one of the prompts to construct a new 10.5" chrome lined barrel for the Grendel. IF the gun balances well (gas system) and functional reliability and durability can be verified for use both with and without a suppressor unit, this gun will join the line up.
DocGKR - Once we have completed the testing I will endeviour to get information to you, for this projectile and several others. I would even now urge you to look to the new 130 grain Swft Scirroco. This bullet is proving to be superb for use against automobile glass and other barriers. Two questions, will you require a test unit in due course? and please ellaborate your thoughts on the use of MoS2 on bullets. I generally thought this was unacceptable for military loads but are now being told the contrary.
Bill Alexander
Section1_Operations
10-07-06, 09:36
I don't have any issues believing the first part. Talking with people that are much more knowledgeable about the 6.8 and 6.5 than me, advise that the 6.5 is very capable at all distances.
I was wondering when you were going to show up Doc! Its not like you to miss a 6.8 thread. :D
C4
Are these same people known subject matter experts when it comes to wound ballistics?
Also, if I'm not mistaken a BC that provides a better trajectory over any distance is different than a comparison of terminal wound performance between rounds.
Section1_Operations
10-07-06, 09:41
We are testing the new 120 Berger projectile currently and the initial results indicate that it does rather well but really want to explore a lot more parameters before releasing the load. The Berger construction is promoting much earlier fragmentation than we have seen to date and I suspect (we have not tested this yet) that the bullet has a lower velocity threshold for fragmentation. This is one of the prompts to construct a new 10.5" chrome lined barrel for the Grendel. IF the gun balances well (gas system) and functional reliability and durability can be verified for use both with and without a suppressor unit, this gun will join the line up.
This would be good news indeed for the Grendel and I await a time when DocGKR can verify a load that does perform like this in the Grendel.
Bill Alexander
10-07-06, 09:54
I think we have all performed a rather pitiful job of answering the question from Pheonixtac that started this thread.
Here is my take.
I would choose a 6.8 because it provides an ability to use the rifle as a hunting weapon as well as providing a whole lot more confidence that the rifle will serve well as an all round peice. I spend a reasonable amount of my spare time outdoors as far away from the crowds as I can get so the ability to deal with a wide variety of North American mammals is important if they take more than a passing interest in my calorific value as a foodstuff or my wallet. Currently there are a number of well made rifles available but I would search out either an LMT or Barrett as I know I can trust these and if there is any problems both companies treat customers very well. I have used the Barrett on several occasions for test work. For ammunition I would go straight to Remington for the soft point offering. The ammo is well made, reliable and runs at safe pressures. Rifle cost is comensurate with the quality you get.
I manufacture the Grendel so obviously my choice is predetermined (I already own the parts needed) but in the absence of this I would not hesitate to consider a 6.8. I have little use for a 5.56.
Bill Alexander
I think we have all performed a rather pitiful job of answering the question from Pheonixtac that started this thread.
Here is my take.
I would choose a 6.8 because it provides an ability to use the rifle as a hunting weapon as well as providing a whole lot more confidence that the rifle will serve well as an all round peice. I spend a reasonable amount of my spare time outdoors as far away from the crowds as I can get so the ability to deal with a wide variety of North American mammals is important if they take more than a passing interest in my calorific value as a foodstuff or my wallet. Currently there are a number of well made rifles available but I would search out either an LMT or Barrett as I know I can trust these and if there is any problems both companies treat customers very well. I have used the Barrett on several occasions for test work. For ammunition I would go straight to Remington for the soft point offering. The ammo is well made, reliable and runs at safe pressures. Rifle cost is comensurate with the quality you get.
I manufacture the Grendel so obviously my choice is predetermined (I already own the parts needed) but in the absence of this I would not hesitate to consider a 6.8. I have little use for a 5.56.
Bill Alexander
Bill,
Where would you draw the line for game weight given your advice? What is the max range you feel it's suitable for hunting? And what barrel lengths are you assuming?
Bill Alexander
10-08-06, 09:43
My particular application assumes the animal in question is about to either eat or rob me so I would not really care about the weight. I am assuming that the first two rounds will distract/frighten the crap, and gain time to empty the rest of the mag or at least keep shooting until the enthusiasm for my person or possesions has wained.
Given the application I would be looking for a barrel that is reasonably easy to carry, either a 16" or better a 14.5" with the flash suppressor permanently attached. (I know it only drops the length by 1/2" overall)
If it was to double as a hunting rig proper I would go with an 18" or 20" but not a heavy profile. At this I would be happy with the rifle out to 200 yards (the limit that I can garantee good shot placement, If those reading will excuse the rant I subscribe to the idea that hunting should encompass a higher degree of field craft and substantially less "long range snipping" I have much greater respect for the hunter who took a shot at 20 yards because he could get that close than the idiot who boasts of 500 yard kills)
For ammunition I would handload as I still regard 110/115g fragmenting .270 cal bullets as varmint loads that can blow up on a shoulder blade or rib. Ideally I would like a 130 grain. With this I would be happy for game up to 400 lbs including pigs.
Bill Alexander
phoenixtac
10-08-06, 09:49
I think we have all performed a rather pitiful job of answering the question from Pheonixtac that started this thread.
Here is my take.
I would choose a 6.8 because it provides an ability to use the rifle as a hunting weapon as well as providing a whole lot more confidence that the rifle will serve well as an all round peice. I spend a reasonable amount of my spare time outdoors as far away from the crowds as I can get so the ability to deal with a wide variety of North American mammals is important if they take more than a passing interest in my calorific value as a foodstuff or my wallet. Currently there are a number of well made rifles available but I would search out either an LMT or Barrett as I know I can trust these and if there is any problems both companies treat customers very well. I have used the Barrett on several occasions for test work. For ammunition I would go straight to Remington for the soft point offering. The ammo is well made, reliable and runs at safe pressures. Rifle cost is comensurate with the quality you get.
I manufacture the Grendel so obviously my choice is predetermined (I already own the parts needed) but in the absence of this I would not hesitate to consider a 6.8. I have little use for a 5.56.
Bill Alexander
I obviously hit a nerve regarding the 6.8 SPC/6.5 Gendel, I hope ALL of you gentlemen can discuss the pro's and con's of both cartridges. The Internet gives us the opportunity to do just that, while moderated for extreme opinions verses substantiated fact, simple as that.
I have been shooting AR platforms for over 20 years, both Militarily, and otherwise, I'm currently evaluating cartridges that will enhance the Warfighters ability to use this platform with enhanced results. I have seen many situations where the limitations of the .223 cartridge has placed the user both civilian, and military in a position of attempting to engage targets at medium to long range, "lets say for the sake of argument 300 to 600 yds", using a weapon that has diminished returns.
I welcome all the opinions, that simply is why I asked the original question in this thread.
My particular application assumes the animal in question is about to either eat or rob me so I would not really care about the weight. I am assuming that the first two rounds will distract/frighten the crap, and gain time to empty the rest of the mag or at least keep shooting until the enthusiasm for my person or possesions has wained.
Given the application I would be looking for a barrel that is reasonably easy to carry, either a 16" or better a 14.5" with the flash suppressor permanently attached. (I know it only drops the length by 1/2" overall)
If it was to double as a hunting rig proper I would go with an 18" or 20" but not a heavy profile. At this I would be happy with the rifle out to 200 yards (the limit that I can garantee good shot placement, If those reading will excuse the rant I subscribe to the idea that hunting should encompass a higher degree of field craft and substantially less "long range snipping" I have much greater respect for the hunter who took a shot at 20 yards because he could get that close than the idiot who boasts of 500 yard kills)
For ammunition I would handload as I still regard 110/115g fragmenting .270 cal bullets as varmint loads that can blow up on a shoulder blade or rib. Ideally I would like a 130 grain. With this I would be happy for game up to 400 lbs including pigs.
Bill Alexander
Very good. Glad to see you are not recommending sniping and are viewing things realistically.
The Bergers we have tested in other calibers have generally performed well. A 6.5 mm Grendel with a 120 gr Berger OTM has good potential! I personally would also like to get a chance to fully assess the potential of the 123 gr SMK, as the 120 gr SMK has been a bit disappointing in terminal performance.
The Swift Scirroco is indeed a superb bullet for intermediate barriers, like auto windshields, as well as for hunting. (For further discussion of intermediate barrier penetration with Scirroco and similar style bullets see: http://www.tacticalforums.com/cgi-bin/tacticalubb/ultimatebb.cgi?ubb=get_topic;f=78;t=001277) I suspect a 6.5 mm Grendel 130 grain Swft Scirroco PT would be just the ticket for game up to 300 lbs or so.
A molybdenum disulfide exterior coating on the bullet jacket does not change projectile terminal performance. However, many of the marksmanship folks recommend that if you choose to use moly bullets--then ONLY shoot moly bullets from that barrel. Beginning in the mid 1990's we began seeing and testing some military ammunition coated with moly and other surface treatments.
We'd love to be able to more thorougly test 6.5 mm Grendel performance in 16" and under barrels!
In direct answer to the thread's initial question, I'd choose the 6.8mm because to date, it has proven to offer the best terminal performance in a compact carbine/assault rifle we have ever tested. Period.
Some random thoughts on the terminal performance characteristics of some of the more common projectiles in 6.8 mm is available here: http://www.tacticalforums.com/cgi-bin/tacticalubb/ultimatebb.cgi?ubb=get_topic;f=78;t=001273
I'm guessing Doc is bound by NDA as to why he is mentioning that the 6.8 saga came out of a search for a better combat cartridge. They tested rounds between 5.56-7.62. While I have no vested interest in either cartidge I have seen a lot more data supporting the 6.8 choice. 6.5 was looked at as well BTW.
I am not criticising the 6.5 Grendle -- I will eventualy own one.
Having shot and killed folk with 5.56mm - and seen the military at war -- I would recommend markmanship practice be job #1. More than half the kids these days dont hit the tgt regardless what round you give them. Even Group SF marksmanship is IMHO terrible -- the conventional side an embarrasment (with notable exceptions in those who do a lot of shooting and courses on their own)
I'm guessing Doc is bound by NDA as to why he is mentioning that the 6.8 saga came out of a search for a better combat cartridge. They tested rounds between 5.56-7.62. While I have no vested interest in either cartidge I have seen a lot more data supporting the 6.8 choice. 6.5 was looked at as well BTW.
I am not criticising the 6.5 Grendle -- I will eventualy own one.
Having shot and killed folk with 5.56mm - and seen the military at war -- I would recommend markmanship practice be job #1. More than half the kids these days dont hit the tgt regardless what round you give them. Even Group SF marksmanship is IMHO terrible -- the conventional side an embarrasment (with notable exceptions in those who do a lot of shooting and courses on their own)
I have to agree with Kevin. Shot placement is everything. I have also attended many a carbine class with Military SF, Secret Service, State Dept., SWAT, etc, etc and a lot of them just couldn't shoot.
My main question and the question that prospective buyers should ask is the 6.8 VASTLY superior to the 5.56 in a heavy bullet configuration (75/77) or is it just somewhat better. IMHO, if it is not vastly superior to the 5.56 in say 77gr, then it really isn't worth it. I know that I can kill someone with a 5.56, hell I can do it with a .22! I want a cartridge that will reach out and touch someone at 800M and do it with authority. This is why the 6.5 looks to be the better choice to me.
C4
If you truly, "want a cartridge that will reach out and touch someone at 800M and do it with authority", then neither the 6.8 mm SPC nor the 6.5 mm Grendel are what you need; a .338 Lap Mag is likely the best and most combat proven choice.
Typical 10-16" barrel combat carbines with red-dot optics like Aimpoint/EOTECH, 4x ACOG's, or 1-4x optics are NOT going to be routinely effective at ID'ing, let alone hitting human targets 800 m in a combat environment. Most experienced folks are reaching for a sniper, indirect fire, or CAS at that range.
Again, as I noted above, 6.8 mm offers substantially better terminal effectiveness compared to ALL 5.56 mm loads, including Mk262, especially through intermediate barriers.
Like I always emphasize, "Only after proper foundational and ongoing repetitive refresher training, cultivating warrior mind-set, and ensuring weapon system reliability do you need to worry about ammunition selection. Most folks would be far better off practicing with what they have, rather than worrying about what is "best". As long as you know your what your weapon and ammo can realistically accomplish, it is all just a matter of training and shot placement."
If you truly, "want a cartridge that will reach out and touch someone at 800M and do it with authority", then neither the 6.8 mm SPC nor the 6.5 mm Grendel are what you need; a .338 Lap Mag is likely the best and most combat proven choice.
Typical 10-16" barrel combat carbines with red-dot optics like Aimpoint/EOTECH, 4x ACOG's, or 1-4x optics are NOT going to be routinely effective at ID'ing, let alone hitting human targets 800 m in a combat environment. Most experienced folks are reaching for a sniper, indirect fire, or CAS at that range.
Again, as I noted above, 6.8 mm offers substantially better terminal effectiveness compared to ALL 5.56 mm loads, including Mk262, especially through intermediate barriers.
Like I always emphasize, "Only after proper foundational and ongoing repetitive refresher training, cultivating warrior mind-set, and ensuring weapon system reliability do you need to worry about ammunition selection. Most folks would be far better off practicing with what they have, rather than worrying about what is "best". As long as you know your what your weapon and ammo can realistically accomplish, it is all just a matter of training and shot placement."
If I REALLY wanted a dedicated sniper rifle, I would get one in a 50. Being realistic, I am looking for a weapon that is VASTLY superior to the 5.56, meaning that it give me extended range and isn't a lot more money to shoot.
From my reading and firing of the 6.8, I don't gather that it is vastly superior to the 5.56. I am sure it is better though, but not enough to warrant the cost. As a Civy, I have to look at the cost of training as Uncle Sugar no longer pays the bills. The 5.56 is cheap to shoot and will put a man down out to 300M's.
C4
I'm with the good Doc on the .338LM issue as .50 is not a practical anti-pers sniper round (sorry for the Hi-jack) - I will start a new thread...
I'm with the good Doc on the .338LM issue as .50 is not a practical anti-pers sniper round (sorry for the Hi-jack) - I will start a new thread...
Being a Navy guy, I would actually prefer a Tomahawk, but for some reason they won't sell me any. Bigger is better right?? :D
I fully understand that that the .338LM is good for sniping.
C4
The 5.56 is cheap to shoot and will put a man down out to 300M's.
C4
Not my experience at all if you are making COM hits. Maybe with a 20" barrel, but certainlty not with 14.5 or less.
Now if you change your docterine like we did and made the point of aim the hips, then you are shooting at roughly the same size target, but lots more bone to fragment on impact. So if you are making hits in the hips, then I would agree that it will drop a man out to 300M.
However, if you are running a 14.5" M4 using M855 making COM hits at 300M, then it's my experience that you better be shooting a couple more rounds. I have no experience with Mk262.
In my experience, extrernal ballistics don't mean squat. A round that has 2,000foot pounds of energy going downrange doesn't mean crap if none of the energy gets transferred into your target.
The 6.8 that I have been using on live targets often leaves no exit wound. That's total energy transfer into the target. I would love to test the 6.5 against living targets, but that is far into my future due to financial strains. If anyone has a 6.5, that uses it for hunting, I think it would be very beneficial to post some information about it's terminal ballistics.
Shark - M855 will kill COM from a 10.5 to 400m
Hitting is the key. I've got two words for people who disagree -- Short Dot :D
No argument that Mk262 is better -- and I dont dispute that 6.8 is better than that.
But saying M855 does not work is flat out wrong.
Shark - M855 will kill COM from a 10.5 to 400m
Hitting is the key. I've got two words for people who disagree -- Short Dot :D
No argument that Mk262 is better -- and I dont dispute that 6.8 is better than that.
But saying M855 does not work is flat out wrong.
I didn't say it didn't work, I just said that in my experience the M855 would not consistently drop targets at that range. It will kill them, but not drop them. I had trouble dropping guys at 100 yards using a SAW para barrel with M855. I may have a different experience than others, but I saw more than just a few people keep going after being hit with M855 through the chest with 14.5" M4's at LESS than 300 meters. Nothing sucks worse than trying to find a wounded combatant in bullrushes or wadi's where you can't see more than 10 feet in front of you.
I don't doubt anything you tell me, but I was just relaying my experiences.:D
Being a dealer, I somewhat have my finger on the pulse of the consumer (is my job to know what is hot). I must talk to a customer about the 6.8 on a weekly basis. The two concerns they have with going to the 6.8 is ammo cost and ammo availability.
Unless NATO picks up the 6.8, which I don't think will happen anytime soon (if at all) the majority of the shooters that will buy 6.8 weapons and ammo are going to be Civilians. So which ever cartridge is cheaper (6.8 or 6.5) and has the most availability, will most likely win the Civy market.
C4
I didn't say it didn't work, I just said that in my experience the M855 would not consistently drop targets at that range. It will kill them, but not drop them. I had trouble dropping guys at 100 yards using a SAW para barrel with M855. I may have a different experience than others, but I saw more than just a few people keep going after being hit with M855 through the chest with 14.5" M4's at LESS than 300 meters. Nothing sucks worse than trying to find a wounded combatant in bullrushes or wadi's where you can't see more than 10 feet in front of you.
I don't doubt anything you tell me, but I was just relaying my experiences.:D
I don't think there is a magic bullet and very few rounds (including a 12ga slug) will immediately turn the lights out. So I cannot believe that the 6.8 is going to "drop" a man either.
I think any standard round that is adopted by the Military will always have to be thought of as a "wounding" round and more than one shot should be fired.
To date, I never had an instructor advise me to fire only one round in order to cancel a threat.
C4
NATO didn't pick-up the .40 S&W, yet it seems to be doing just fine in the market...
NATO didn't pick-up the .40 S&W, yet it seems to be doing just fine in the market...
Yes, but they had a Federal agency (FBI) that was pushing for it. To date, I don't know of any large Federal agency pushing for the 6.8 (please correct me if I am wrong).
Civy shooters tend to follow what the groups like the FBI or Military use so that is why the 40 has done so well.
C4
My humble opinion, and worth exactly what you paid for it, assuming we're still going to put crappy triggers, non-free floated barrels and chrome-lined barrels on the bulk of the forces' weapons, 5.56, 6.5, 6.8 is largely irrelevant. You can still get hits with these configs, but you'll never get hits consistently. So why we let the long range scenario drive the debate, I'll never understand.
If I were king for a day I'd pick a system that's optimized for the 0-300 meter envelope, is logistically supportable and provide decent operational reliability and longevity. I'd want something that results in a more immediate effect than what occurs today with 5.56. I'd want something that could go through auto sheetmetal and glass and still inflict desired effects at the receiving end. But whatever performance I'd get outside that envelope, I just accept it. And if that performance wasn't good enough, then I'd come up with dedicated weapons platforms and training programs to handle those situations, but I wouldn't waste my time or resources trying to get the whole force up to that capability level.
To look at it another way, if today's platform and soldier has a 10-20% hit probability out at 600-800, I doubt simply by switching to a flat 6.5 caliber hit percentage is going to go up measurably. What would be gained, maybe another 5%? If you need big performance gains, you need more specialized equipment and training. Again, JMHO.
My humble opinion, and worth exactly what you paid for it, assuming we're still going to put crappy triggers, non-free floated barrels and chrome-lined barrels on the bulk of the forces' weapons, 5.56, 6.5, 6.8 is largely irrelevant. You can still get hits with these configs, but you'll never get hits consistently. So why we let the long range scenario drive the debate, I'll never understand.
If I were king for a day I'd pick a system that's optimized for the 0-300 meter envelope, is logistically supportable and provide decent operational reliability and longevity. I'd want something that results in a more immediate effect than what occurs today with 5.56. I'd want something that could go through auto sheetmetal and glass and still inflict desired effects at the receiving end. But whatever performance I'd get outside that envelope, I just accept it. And if that performance wasn't good enough, then I'd come up with dedicated weapons platforms and training programs to handle those situations, but I wouldn't waste my time or resources trying to get the whole force up to that capability level.
To look at it another way, if today's platform and soldier has a 10-20% hit probability out at 600-800, I doubt simply by switching to a flat 6.5 caliber hit percentage is going to go up measurably. What would be gained, maybe another 5%? If you need big performance gains, you need more specialized equipment and training. Again, JMHO.
I think you are right. The majority of fighting is 300M and in. As we know, one of the reasons why the Military switched to the 5.56 was so the average soldier could carry more rounds. I imagine that if we never switched, soldiers would be complaining about running out of ammo. I don't know that there is a right or wrong answer here.
I personally am in favor of more ammo VS less ammo. Then again, I believe that I can hit what I am aiming at. I have to imagine that when the switch to the 5.56 was made, they knew that SOME of our soldiers couldn't hit a house from 50yds so giving them more chances simply increased their odds.
C4
Being a dealer, I somewhat have my finger on the pulse of the consumer (is my job to know what is hot). I must talk to a customer about the 6.8 on a weekly basis. The two concerns they have with going to the 6.8 is ammo cost and ammo availability.
Unless NATO picks up the 6.8, which I don't think will happen anytime soon (if at all) the majority of the shooters that will buy 6.8 weapons and ammo are going to be Civilians. So which ever cartridge is cheaper (6.8 or 6.5) and has the most availability, will most likely win the Civy market.
C4
The money thing is very key for those of us paying for both ammo and training out of our own pockets.
I think it would be important to train with what you shoot.
I recently took a 5 day HRCC class from Tactical Response.
Price was $1250
We shot about 4000 rounds, i used Black Hills 55 grn that I managed to get a deal on. (after the first day when Wolf killed my AR, but lets just assume I shot the Black hills for the whole class)
Price was $220/1000 or $880 for 4000 rounds.
Now if I took that same class shooting 6.8 SPC then let's look at the cost of ammo. I'm not an expert on the pricing, so I'll just use the numbers I found at Sportsman's Guide which is $53/100
so we have $53/100 or $2120 for 4000 rounds
That is a real difference, and a real ****ing problem.
I'm choosing the 6.5 for 2 things. Long range shooting competition Ala Zack's PRTC match, and hunting. in both cases while the ammo may still be pricey, we are comparing more to match or hunting grade .308 loadings and the prices are similar. Plus I'll never shoot the volume of the ammo that I do with 5.56.
I agree with you mudbug. That why to shoot much 6.8 or 6.5 you will need to reload it. It only makes sense.
Liek you I will never shoot the amount of 6.8, that I do 556, strictly from a $$$ standpoint. I only have around 750 rds of 6.8 right now, but a few thousand of 556.
I think as more gun makers start making weapons for it, the price of ammo will come down. 6.8 is no more $$ than 308, but MOST people shoot 308 from a bolt gun, where as most peopel shoot a 6.8 through an AR. hence they fire ALOT more ammo. More ammo = More $$$
My local walmart carries Remington 6.8 ammo. Who woulda thunk it. If it was me I would buy 100 rds from SSA, and some brass. Shoot the ammo, then start reloading. The local gun store stocks 6.8 ammo as well. Remington OTM @ $13.xx a box if memory serves. it may even be cheaper cause I can get 3 box's for $40 out the door. So I usually go by and get 3 boxs a week, and just stack it up at the house for a rainy day. I like to shoot the SSA ammo better anyway but the remington ammo shoots fine too. You just have to police the brass and reload it.
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