View Full Version : PDW length barrels.....300BLK or 5.56?
Barrels less than 10.5". Let's say 8" or 9". Let's also establish that we're talking about out to 200 meters max. Now a PDW is obviously intended for CQB-type distances but if need be you could reach out and touch someone at intermediate ranges. Not talking a hill-to-hill shootout in Afghanistan but within 200m.
From chrono data I've seen over the years 5.56 NATO (not talking .223) starts to really fall off terminal performance-wise with barrels < 10.5". However, 300BLK is designed for short-azz barrels, namely in the "PDW" envelope I'm referring to.
So the hypothesis I'm putting forward is that in barrels shorter than 10.5" the 300BLK will surpass 5.56 terminal performance out to 200 meters. You go 10.5" or longer and the 5.56 shines (with good ammo of course).
Fire away. :)
Rayrevolver
12-04-17, 07:33
So the hypothesis I'm putting forward is that in barrels shorter than 10.5" the 300BLK will surpass 5.56 terminal performance out to 200 meters. You go 10.5" or longer and the 5.56 shines (with good ammo of course).
Fire away. :)
Lol. I'll bite, although I am not the most versed with 300BLK.
Per R Silvers PDF, find the Max Effective Range slide:
300 BLK (125gr @ 2220fps) from a 9 inch barrel has the same energy at the muzzle as a 14.5 inch M4, and about 5% more energy at 440 meters.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwjh5I2Ju_DXAhVN4WMKHeEBDW4QFggvMAE&url=https%3A%2F%2Fndiastorage.blob.core.usgovcloudapi.net%2Fndia%2F2012%2Farmaments%2FWednesday13590Silvers.pdf&usg=AOvVaw2KvaaZ923PEYqR62ezc0nq
I would put that inside 200 meters, the 9 inch 300 BLK is more effective that any sized 5.56 (based on the "size efficiency" of the package). You can have supersonic mags and subsonic mags.
Nightvisionary
12-04-17, 16:04
Lol. I'll bite, although I am not the most versed with 300BLK.
Per R Silvers PDF, find the Max Effective Range slide:
300 BLK (125gr @ 2220fps) from a 9 inch barrel has the same energy at the muzzle as a 14.5 inch M4, and about 5% more energy at 440 meters.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwjh5I2Ju_DXAhVN4WMKHeEBDW4QFggvMAE&url=https%3A%2F%2Fndiastorage.blob.core.usgovcloudapi.net%2Fndia%2F2012%2Farmaments%2FWednesday13590Silvers.pdf&usg=AOvVaw2KvaaZ923PEYqR62ezc0nq
I would put that inside 200 meters, the 9 inch 300 BLK is more effective that any sized 5.56 (based on the "size efficiency" of the package). You can have supersonic mags and subsonic mags.
I was a big drinker of the R. Silvers 300Blk cool aid for awhile. The velocity you have listed is actually for a 125 grain bullet through a 16 inch barrel. 9 inch velocity is 2050. Silvers/AAC purposefully compared results from a 16 inch 300 blackout barrel to a 14.5 5.56 barrels to cherry pick results but I do think the OP is correct in his assumption. I plan on jumping back into 300 BLK in the near future with an 8.5-9 inch barrel. With hand loads the 110 grain Barnes TAC TX blacktip should achieve 2250-2300 without much problem ( I pushed them to 2500 in a 16 inch no problem)and they will offer some expansion down to 1350-1400 FPS so I think the cartridge with that bullet definitely has an advantage over 5.56 in sub 10.5 barrels.
Sorry for the quality of this image. I had it saved from several years ago, and don't remember the source. The go to projectile today is still the 110 gr. Barnes TAC TX as NV mentioned.
49058
I was a big drinker of the R. Silvers 300Blk cool aid for awhile. The velocity you have listed is actually for a 125 grain bullet through a 16 inch barrel. 9 inch velocity is 2050. Silvers/AAC purposefully compared results from a 16 inch 300 blackout barrel to a 14.5 5.56 barrels to cherry pick results but I do think the OP is correct in his assumption. I plan on jumping back into 300 BLK in the near future with an 8.5-9 inch barrel. With hand loads the 110 grain Barnes TAC TX blacktip should achieve 2250-2300 without much problem ( I pushed them to 2500 in a 16 inch no problem)and they will offer some expansion down to 1350-1400 FPS so I think the cartridge with that bullet definitely has an advantage over 5.56 in sub 10.5 barrels.
Yeah, it's a very narrow niche category but in < 10.5" barrels the 300BLK is in it's element. The 5.56 is designed for "longer" barrels than 8" or 9" and IMHO will overtake the 300 in those categories. But the little PDW scene? I'll take 300BLK.
turnburglar
12-04-17, 19:15
If burning powder is the name of the game- a larger bore will always do better than a smaller one.
338 federal does better than 308
6.5 grendel willl do better in a shorter barrel than 224 valkyrie
300blk will do better than 556 ect
If burning powder is the name of the game- a larger bore will always do better than a smaller one.
338 federal does better than 308
6.5 grendel willl do better in a shorter barrel than 224 valkyrie
300blk will do better than 556 ect
Good point.
Rayrevolver
12-05-17, 15:02
Found some actual user numbers last night from both TOS and M4C. With respect to muzzle energy, Barnes 5.56 70gr in a 14.5" barrel = Barnes 300BLK 110gr in a 9" barrel
Just challenging your hypothesis:
If you want a 14.5" or shorter, go 300BLK. If you want a 16" then get a 5.56.
For whatever the reason, I like shooting my suppressed 11.5" 5.56 better than a suppressed 9" 300BLK. If I had to choose 1 to keep, it would be the 5.56.
Just based on energy numbers, I am not sure how you can defend a 14.5" 5.56 when a 9" 300BLK can get the job done. Real world, SBR issues, rail space, ammo costs etc mean its not just an energy numbers issue of course.
I always looked at anything under 10.5" in 5.56 as a range toy/noise maker. My personal preference is 11.5-14.5" in 5.56. I'd be willing to go shorter in .300blk, which puts it in PDW territory.
You guys are making me want (need) a 300. Do 300 supers from a 10.5 suppress significantly better than 5.56?
friendlyfireisnt
12-05-17, 17:23
Energy comparisons are useful, but aren't the full story.
Energy is only one component of what makes a bullet successful.
Let's give an example using .300blk. From a 10.x" barrel, with the 110gr Barnes you are getting about 2,200fps, and with a 147gr FMJ you will get around 1,900fps.
Plugging those velocities into JBM shows the 110gr Barnes as having 565ft/lbs of energy at 300 yards, and the 147gr having 700ft/lbs of energy at 300 yards. Yet we know that the 147gr FMJ is not nearly as effective of a bullet as the 110gr Barnes.
Best to look at energy as the means in which the bullet is able to perform it's work. That work can be categorized as penetration, expansion and/or fragmentation, as well as potential for tissue damage. But that ability to do work (energy) only matters in relationship to the materials available and the engineering (or design) of the bullet. The 147gr bullet has more material and more energy, but you can't say that it's going to do more damage to tissue then the 110gr Barnes, with less energy and less material, but a better design.
So comparing energy numbers isn't really ever an apples-to-apples comparison.
A better way of looking at it, in my mind at least, is to start the process with an identification of what you want the bullet to be able to accomplish at particular distances out of a particular barrel length, and then from there identify what caliber and bullet combination meets that requirement.
For example, to me a PDW weapon is one that is concealable, quick to deploy, should be accurate enough to 200+ yards, have solid terminal ballistics (ie. be able to penetrate at least 12" of 10% gel) and since a PDW is likely to be used in or around vehicles, perform even if the projectile hits an intermediate barrier (auto glass, sheet metal, etc).
Both 5.56 and .300blk have rounds that are capable of that.
So the question becomes which one does it better?
There are more than a few gel tests on both and from there we can get the following info:
The 5.56/.223 62gr Fusion (out of a 16" barrel) will have a max expansion of around 0.535", min expansion of .352". Average expansion of about .443". A shorter barrel will affect those numbers.
The .300blk 110gr Blacktip will have a max expansion of around 0.782" and a min expansion of .491". Depending on the test, the average seems to be in the .585" - .636" range. Those numbers come from 8"-10" barrels.
The .300blk has a larger temporary stretch cavity, which isn't an end all, be all, but it's something to notice. It also penetrates deeper.
The 5.56 will lose initial velocity faster as you go to shorter barrels than the .300blk, due to the power burn rate.
For those reasons, I keep a 10.3" .300blk (and am considering a 8.x" .300blk). At the same time, due to cost and availability of the 110gr blacktips, I also keep a pair of 11.3/11.5" 5.56 SBR's loaded with Federal Fusion.
There's a few other items to look at beyond terminal ballistics. Function is paramount for serious use, and some other considerations that we could look into. We want to fall into a place where we have the widest spans of requirements overlapping each other superimposed to better fit the role.
While a 5.56 carbine gas with the carbine action suit many, descending in barrel length to less than 11.5" can find many in a wider span using 300 Blackout pistol gas with a rifle like or A5 action.
The magazine issues involved favor the rifle or rifle like A5 to reduce MRBS issues for either chambering for function. The higher massed 300 Blackout projectiles benefit function with more time in bolt over travel to the magazine with a more rifle like action, than a shorter time duration carbine action for proper round presentation in the magazine to the chamber for function.
There's more than this that we can look at here.
I find this thread very timely. I am thinking about moving from 9mm mini uzi or MP5K both semi auto only to a PDW that is a rifle round.
I spent so much of my career with a 10.5 or 11.5 M16, and I know that we tried to get short 5.56 guns to work 100% and just stuck with rifles for overt work and mini Uzi for covert.
But I really would like to get a 100% reliable rifle with a 7.5 to 8.5" barrel that will not be the same as shooting a 22 magnum. I am lucky as I view this as a max range of 50 meter weapon.
What is the expansion threshold for 110gr vmax?
My current thinking is 556 down to 11.5, any shorter, get a 7-9” 300blk.
10.5-16” seems to be 6.8 territory if your into that (not for me).
I’ll be building a 300 upper soon, 8-9”, but I need to decide if I want a short gun with silencer capability, or build it as a subsonic, full time suprpressed gun with 13”handguard. From what I’ve read, supers with a setup like that are a no-go.
Anyway - full circle- it would come down to how far out your ammo will expand. Energy is potential, it doesn’t mean anything by itself. In other words, it’s not a wounding mechanism.
Has anyone made up a Venn diagram that encompasses what we are discussing?
I'm convinced that the 300BLK outshines the 5.56 in short barrel applications but I don't have data to add to the discussion.
Sent from my Pixel using Tapatalk
What is the expansion threshold for 110gr vmax?
Doesn't really matter. Do not trust a 300 BLK load with an OAL much shorter than a normal 5.56, there is too much potential for them to move forward and jamb the stack.
What is the expansion threshold for 110gr vmax?
My current thinking is 556 down to 11.5, any shorter, get a 7-9” 300blk.
10.5-16” seems to be 6.8 territory if your into that (not for me).
I’ll be building a 300 upper soon, 8-9”, but I need to decide if I want a short gun with silencer capability, or build it as a subsonic, full time suprpressed gun with 13”handguard. From what I’ve read, supers with a setup like that are a no-go.
Anyway - full circle- it would come down to how far out your ammo will expand. Energy is potential, it doesn’t mean anything by itself. In other words, it’s not a wounding mechanism.
Depends on the can. A short can with a Ti tube and inconel or stellite blast baffle and inconel or 416SS baffles is going be fine for anything except multiple mag dumps. The issues you're talking about come from trying to run supers in a short barrel with a multi-cal can that's basically a 9mm can rated for .300 subs. Stick with a 7.62 based can and supers will be fine.
I always looked at anything under 10.5" in 5.56 as a range toy/noise maker. My personal preference is 11.5-14.5" in 5.56. I'd be willing to go shorter in .300blk, which puts it in PDW territory.
That was the small niche group of weapons I was suggesting that 300BLK could exceed 5.56 in.
What is the expansion threshold for 110gr vmax?
My current thinking is 556 down to 11.5, any shorter, get a 7-9” 300blk.
10.5-16” seems to be 6.8 territory if your into that (not for me).
I’ll be building a 300 upper soon, 8-9”, but I need to decide if I want a short gun with silencer capability, or build it as a subsonic, full time suprpressed gun with 13”handguard. From what I’ve read, supers with a setup like that are a no-go.
Anyway - full circle- it would come down to how far out your ammo will expand. Energy is potential, it doesn’t mean anything by itself. In other words, it’s not a wounding mechanism.
Pretty much what I was proposing, although I'd even use 5.56 with a 10.5" barrel. Shorter than that (and we're in PDW territory then) and I'll take 300BLK.
Has anyone made up a Venn diagram that encompasses what we are discussing?
I'm convinced that the 300BLK outshines the 5.56 in short barrel applications but I don't have data to add to the discussion.
Sent from my Pixel using Tapatalk
Variations of Venn's are used all the time. For something like this, you'd be looking at a comparison between some pretty complex diagrams to interpret for either. That is unless you go overly basic and overly basic is your best outcome for that.
In general, does 300BLK do anything better than 5.56 in the 11.5-16" range?
They can with supersonic loads.
They can with supersonic loads.
My understanding is that subsonic 300BLK is akin to handgun terminal ballistics. Therefore, it is worthless to me in a defense situation.
Official Kremlin Transmission
What makes you think that handguns can not be effective? That is the highest use outside of a battlefield. I agree that 300 BO offers some better performance overall with supers, but some subsonic rounds do perform well.
What makes you think that handguns can not be effective? That is the highest use outside of a battlefield. I agree that 300 BO offers some better performance overall with supers, but some subsonic rounds do perform well.
If I'm shooting a rifle, I'd prefer it to perform like a rifle.
Which subsonic 300BLK rounds do you like?
There's a few commercially available projectiles in a lead alloy popular in another forum, some into supersonic levels. There are a few solid copper options available. There are some copper jacketed rounds that could enter the commercial market if demand allowed a production scale to make the price more feasible.
The supers available now is more of my focus for a PDW type of system, but I would not overlook some subsonic capabilities.
daddyusmaximus
12-06-17, 19:58
If I'm shooting a rifle, I'd prefer it to perform like a rifle.
Which subsonic 300BLK rounds do you like?
This...
My home defense gun is a 11.3" .300 and I run it with everybody's fav 110 gr Vortex. Pricey, and hard to find, but I pick some up whenever I can find it. If you need a short gun, but want the maximum punch, this is my answer to the problem. I do like the capability of going to subs with a can, and I hope to explore that one day, but my goal was a short package that hits hard, and the 5.56/.223 just gives up too much in the short guns. Quiet can wait for now. I want it to hit like a rifle. In fact, I wanted to go real short, 8 or 9" but felt that the 11.3" was a happy medium. Again, I knew I was gonna shoot supers and wanted the hardest hitting round. I retain the opting of going shorter... Anybody have data in the 110 gr Vortex out of a 8 or 9" tube?
This...
My home defense gun is a 11.3" .300 and I run it with everybody's fav 110 gr Vortex. Pricey, and hard to find, but I pick some up whenever I can find it. If you need a short gun, but want the maximum punch, this is my answer to the problem. I do like the capability of going to subs with a can, and I hope to explore that one day, but my goal was a short package that hits hard, and the 5.56/.223 just gives up too much in the short guns. Quiet can wait for now. I want it to hit like a rifle. In fact, I wanted to go real short, 8 or 9" but felt that the 11.3" was a happy medium. Again, I knew I was gonna shoot supers and wanted the hardest hitting round. I retain the opting of going shorter... Anybody have data in the 110 gr Vortex out of a 8 or 9" tube?
https://www.m4carbine.net/showthread.php?84557-300-blackout-terminal-ballistics/page3
See post#56.
I had this same dilemma... I ended up going with a 8.5 inch 5.56 because the ammo was cheaper so I could practice more. If you are wiling to be selective with the ammo you use, you can still get very good performance inside of 100 to 150 yards with the 8.5 inch velocities. The 10.5 does have better ballistics and I will probably end up getting a 10.5 inch upper also in 5.56 but I don't really see the need to use a 300 blk.
If I was doing it over, I would have just gone with a 10.5 vs the 8.5 inch because I don't think the 2" difference is all that noticeable...If I were to choose another caliber for a short barrel it would be 6.8spc, since both it and 300 BLK are expensive and I don't think 300 blk does anything the 6.8 doesn't do better.. Having said that, Sure the 300 blk and 6.8 have more energy then the 5.56, but there isn't varying levels of dead, and at the close ranges a PDW is intended to be used at all three calibers will leave a target equally dead.
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