AK and AR pistols

[RichardR]

And 7.62 leaves my 10 inch barrel almost as fast as that 5.56 and weighs almost three times as much.

The point of my post was that the muzzle velocity you lose from going from 16 to 7-10 inches on a 5.56 rifle is far more drastic than going from 16 to 10 inches on a 7.62. I only lose about 100-150 fps whereas someone with a 5.56 is losing anywhere from 300-500 fps.

A 55 gr round moving at 2,200 fps is comparable to a .22 magnum which can move out at around 2,000 fps on a 40 gr round.

Dunno, seems to make sense to me. Doesn't really matter to most people what the round performance is if they're shooting paper for fun. My AK pistol is a SHTF back up.

*shrug* I don't think anyone is arguing that there isn't a reduction in both velocity & thus energy the shorter you go on an AR's barrel length, or that the 5.56x45mm vs 7.62x39mm makes a better pistol/SBR platform.

I was more interested in dispelling one of those common "gun forum myths" that short barreled AR's don't have enough energy to be anymore useful than a .22WRM, or that they only good "just for fun" which is simply not true.

In my opinion & experience a 55 grain bullet, pushed out of a 7.5" AR barrel @ 2,350fps (average fps between the 2,200-2,500fps range previously posted) is still quite potent, they are infact more potent than a P90 or MP7, which no-one seems to question their meger cartridges ability to preform their inteded roles as PDW's (personal defense weapons).

I own & shoot multiple rifles chambered in both cartridges of all sorts of various barrel length configurations, so I'm not "fan-boying" one over another, just trying to clear up a common misconception.

[TMF]

[quote data-cid='968888' name='RichardR' timestamp='1368305521' post='968888'][quote data-cid='968865' name='TMF' timestamp='1368301463']



I was more interested in dispelling one of those common "gun forum myths" that short barreled AR's don't have enough energy to be anymore useful than a .22WRM, or that they only good "just for fun" which is simply not true.


In my opinion & experience a 55 grain bullet, pushed out of a 7.5" AR barrel @ 2,350fps (average fps between the 2,200-2,500fps range previously posted) is still quite potent, [/quote]

I'm a little skeptical of 2,500 fps with standard store bought 55 gr ammo. Not trying to call you a liar, I just haven't heard of something burning that efficient.

What I was offering was my reasoning on why I went AK over AR. Based on the numbers an AK is only losing 5-10% of its energy going from a standard length barrel to a short barrel. 5.56 is losing 20% or more. That was the defining reason. I realize that isn't a big deal to most, but it was for me.

On the .22 mag, the reference is to the size and speed. Yes, 5.56 out of a short barrel is faster, but close enough for me to compare the two, especially when you calculate energy. If I was going to do an AR pistol I would be doing it in 6.8... if ammo ever comes available.

Lastly, when oiling myself up and donning '80s era Soviet camo pants whilst yelling "wolverines", it isn't the same with an AR pistol.

[Jonnin]

I haved a scoped plr-16, its reasonably accurate out to about 200 yards, as in it would work for hunting/"defense" or whatever at that range.  It could probably do better, I have not spent enough time working up target ammo for it specifically.   Its not a sniper rifle. 

 

At any range where it would be a replacement for an AR or AK, its more than fine -- its really a close quarters build anyway.

[RichardR]

ata-cid='968888' name='RichardR' timestamp='1368305521' post='968888']

I'm a little skeptical of 2,500 fps with standard store bought 55 gr ammo. Not trying to call you a liar, I just haven't heard of something burning that efficient.

On the .22 mag, the reference is to the size and speed. Yes, 5.56 out of a short barrel is faster, but close enough for me to compare the two, especially when you calculate energy.

The high end (2,500fps) is obtainable if you use Hornady Superformance or Buffalo Bore ammunition, but most folks don't which is why I choose to use the 2,350fps middle-ground velocitiies in my examples.

And I still don't how you can honestly & with a straight face can still compare the two cartridges, even with a 16" barrel .22WRM isn't even close when it is pushing a 50 grain bullet, especially if it is pushing it out of a pistol length barrel.

Granted a 20+" barreled .22WRM pushing a 40 grain bullet can get up to 2,000fps but at this point the arguement gets silly IMHO, because not only have we A.) Gave the .22WRM three times the barrel length of the AR. B.) Gave the .22WRM 1/4th of the bullet wieght to push & C.) Are ignoring the additional 350fps (on average) that the 5.56 achieves out of a much shorter barrel while pushing a heavier bullet.

So yea I guess minus all of the above differences between the two they are exacly the same! All teasing aside it has been an enjoyable conversation & hopefully someone else who's on the fence trying to decide between the two finds our discussion useful.

Anyway yes I will agree with you that the 7.62x39mm doesn't loose quite as much velocity when the barrel length is shortened, but that doesn't minimize the effectiveness of the SBR'd or pistol-length 5.56 chambered AR's for use as a PDW.

You seemed more focused on what the 5.56 cartridge looses when the barrels are shortened, instead of what potential it still retains ...

[Guest Lester Weevils]

I had an AR pistol. Like Steel said, huge fireball with factory loads. Wear plugs and muffs to shoot it!

 

I tried loading down, but never got a load that was comfortable to shoot, that would cycle the action. With full power Lake City ammo, it would shoot dime size groups at 25 yards off a bipod. It was fun for a while, but I traded it for a .223 pistol that I could hit something with. A Contender.

 

Another PLR-16 fella here, kinda like an AK action that shoots 5.56. It is mainly a range toy.

 

A bipod might be useful on the thang for longer-distance shooting however. Reckon there are any "reasonable" odds of getting in trouble for a fold-up bipod, with the authorities trying to claim that it is equivalent to a vertical fore-grip?

[RichardR]

Another PLR-16 fella here, kinda like an AK action that shoots 5.56. It is mainly a range toy.

A bipod might be useful on the thang for longer-distance shooting however. Reckon there are any "reasonable" odds of getting in trouble for a fold-up bipod, with the authorities trying to claim that it is equivalent to a vertical fore-grip?

Doubt you'd get any grief over a traditional bi-pod, I wouldn't suggest adding one of those "grip-pods" on a pistol though.

Anyway TMF compairing velocities between cartridges can be mis-leading, especially when other mitigating factors like barrel lengths & bullet weights are not identical (or even close).

I think if we used muzzle energy numbers it would be much less miss-leading, since that is the basis/root of how potent or impotent a cartridge has the potential to be anyway.

So let's take a 55 grain bullet, traveling at the 2350fps average, which according to Hornady's ballistic calculator equals roughly 670ish ft/lbs of energy, which oddly enough is over twice the energy of a 50 grain .22WRM (300 ft/lbs) fired from a full-length (24") rifle barrel.

While that is severly diminished from a 5.56 fired from a 16" AR (about roughly half), that remaining 670 ft/lbs of energy is still within .357 magnum, not .22 magnum territory.

I hope that this helps put this particular "rumor" to pasture, at least here on TGO.

[Oh Shoot]

I want to chrono my 10.5 AR with some different ammo, but I see various reports and charts showing 2500 to 2900 for various 55gr loads out of that length.

 

Let's be even more conservative, and say 2350-2400 at worst. That's still not too shoddy ya know, for hollow point or soft nose ammo, even assuming you don't get tumbling or fragmentation at the lower end.

 

Can tell you with iron sights, I don't see any significant POI diff at 50 and 100 yards between my AR pistol and rifles with same cartridge, so I suspect it will do the job at those distances adequately.

 

If you're needing to shoot 'bout any pistol past 100 yards you probably didn't bring the appropriate firearm for the purpose.

 

- OS

Edited May 12, 2013 by Oh Shoot

[TMF]

You seemed more focused on what the 5.56 cartridge looses when the barrels are shortened, instead of what potential it still retains ...

Yes I am. I'm a bang for your buck kinda guy, so losing that muzzle velocity makes me feel cheated, as silly as that sounds. Keep in mind I have four 5.56 rifles, so I'm not fundamentally opposed to the cartridge. Good conversation though and hopefully contributes to an educated decision for the OP.

[RichardR]

I want to chrono my 10.5 AR with some different ammo, but I see various reports and charts showing 2500 to 2900 for various 55gr loads out of that length.

Let's be even more conservative, and say 2350-2400 at worst. That's still not too shoddy ya know, for hollow point or soft nose ammo, even assuming you don't get tumbling or fragmentation at the lower end.

Can tell you with iron sights, I don't see any significant POI diff at 50 and 100 yards between my AR pistol and rifles with same cartridge, so I suspect it will do the job at those distances adequately.

If you're needing to shoot 'bout any pistol past 100 yards you probably didn't bring the appropriate firearm for the purpose.

- OS

Yea with a 10.5" barrel you should still easily expect to get reliable tumbling & fragmentation with 55 or even 62 grain FMJ bullets at 100-150 yds or less.

Like you, the accuracy of my shorty AR's are also "on-par" so to speak @ 100 yds with their longer carbine/rifle breathern, but my using an Eotech on mine helps a lot with that.

[RichardR]

Yes I am. I'm a bang for your buck kinda guy, so losing that muzzle velocity makes me feel cheated, as silly as that sounds. Keep in mind I have four 5.56 rifles, so I'm not fundamentally opposed to the cartridge. Good conversation though and hopefully contributes to an educated decision for the OP.

Meh, no worries man doesn't seem all that silly.

I try to look at it from a "current capability" standpoint, as in what exactly is this piece of equipment capable or not capable of, as it sits.

So how the 5.56x45mm or 7.62x39mm cartridges perform in their carbine &/or full sized service rifle configurations was irrelevant to how I evaluated how the cartridges performed when fired out of the shorty's.

I can tell you that a 55 grain FMJ 5.56x45mm fired from a 7.5" SBR or pistol will easily zip right through both sides of level IIIa body armor @ 50 yds.

Granted so will a 7.62x39mm fired from a shorty, but I wasn't expecting a 55 grainer out of such a short barrel to penetrate both sides of the armor, I have a couple extra IIIa kevlar panels if you would like to see it for yourself (you have to buy the beer though).

But yea I've also enjoyed our conversation, hopefully the OP &/or some of our other fellow TGO'ers all enjoyed it as well & maybe learned something along the way that helped them spend even more of their hard-earned dough.

[Guest Aces&8s]

To the OP --

 

I cannot speak as to muzzle velocities, ballistics, expansion rates, nor projectile penetration, but I can tell you this:  I own an AR pistol which I built from parts, and it is one of my favorite guns to shoot.  Big bang, big flame - it is unlike any other firearm I own.  Mine consists of the following:

 

A2 upper

Doublestar BCG

Palmetto State lower

Doublestar 7.5" barrel

YHM free float handguard

DPMS lower parts kit

Doublestar pistol buffer tube

H2 buffer

and rather than the Pig, I went with the Levang linear comp (it does a great job, BTW).

 

I have not had to "tune" mine in terms of gas system, but it does like to run a little wet.  It will shoot anything I feed it, including steel case stuff, and the accuracy is good.  But to be honest, pinpoint accuracy is not what I am going for with this gun...  after a few shots, I lose all discipline and just start cranking out rounds while yelling my "war cry"...  yeah, I have no shame.   :pleased:

[Jonnin]

The thing about the shorter barrel velocity loss in 223 is its ability to tumble.   I do not know --- its all garbage in and garbage out from the web, with little in the way of science behind the few tests on the subject ---  but supposedly the 223 will no longer tumble if it loses too much velocity.    This is easy to deal with (use the hollow point / rubber tipped ammo) if it is true, but my understanding was that is the biggest thing to pay attention to when using a short 223 @ a reduced velocity.    You do not want to have it for defense if all it can do is poke a 22 caliber hole. 

[RichardR]

The thing about the shorter barrel velocity loss in 223 is its ability to tumble. I do not know --- its all garbage in and garbage out from the web, with little in the way of science behind the few tests on the subject --- but supposedly the 223 will no longer tumble if it loses too much velocity. This is easy to deal with (use the hollow point / rubber tipped ammo) if it is true, but my understanding was that is the biggest thing to pay attention to when using a short 223 @ a reduced velocity. You do not want to have it for defense if all it can do is poke a 22 caliber hole.

That is a common misconception, however even without fragentation or tumbling or expansion the temporary cavitation, (ie: trauma & shock) caused by a 55 grain FMJ travelling at 2350fps would most likely be instantly incapacitating even if not ultimately fatal, if we are talking a COM hit on an attacker.

Granted both the temporary cavitation & permenant wound channel are both much greater if the bullet tumbles &/or fragments, but it is not absent from terminal equasions even if the bullet doesn't.

I am not sure if I explained that as well as I could have, but essentially it boils down to there is still plenty of "shock/trauma" caused at those velocities to immobalize (if not outright kill) regardless of (or absent any) tumbling/fragmentation/expansion of any bullet of any caliber of any weight, I'll try to find the term paper I submitted while back in college which closely examined the terminal effects of temporary cavitation of high velocity bullets vs the permanent wound channels of larger, heavier bullets.

It is interesting stuff, which is of course is also the basis behind the trend of militaries around the world developing smaller caliber higher velocity rounds in the late 60's & early 70's (not my term paper, just the theory my paper was based on).

Of course the smaller caliber, higher velocity rounds are even more effective when factors such fragmentation, tumbling &/or expansion are added, even in the absence of those factors the terminal effects of temporary cavitation are still quite effective in neutralizing a threat.

So basically we're not just talking about a .22 sized "through & through" hole, that may or may not hit something important, we are talking about millions upon millions of instantly ruptured capularies, torn nerves, massive internal bleeding & organ bruising caused soley by the temporary cavitation surrounding that .22 sized hole.

Nasty stuff to think about, I certainly don't ever want to experience it first hand, but for HD/SD I still prefer 00 buck ... nothing else even comes close in effectiveness for CQC in my opinion, except for maybe 000 buck LOL ...

[Jonnin]

Yes, in theory.  But there was an awful lot of talk about the 556 and  failure to stop hits vs the ultra thin targets in the last couple of wars....   it poked a hole in the target and dumped no energy, made little more wound than a .22 LR to hear some of the descriptions.   I dunno, I was not there, and the internet isnt exactly reliable info.

 

Could be bad info / misconception.   Could be true.  For me, my pistol is not using FMJ though, just in case.

[RichardR]

Yes, in theory. But there was an awful lot of talk about the 556 and failure to stop hits vs the ultra thin targets in the last couple of wars.... it poked a hole in the target and dumped no energy, made little more wound than a .22 LR to hear some of the descriptions. I dunno, I was not there, and the internet isnt exactly reliable info.

Could be bad info / misconception. Could be true. For me, my pistol is not using FMJ though, just in case.

Without more details (bullet weight, velocity, range from target, autopsy reports, etc) It'd be difficult to say.

Granted the 5.56x45mm isn't the best choice for long-range engagements, which would have been more typical in Afgan than in Iraq, but could literally happen just about anywhere.

Neither is it the best choice for short barreled applications, but it is widely availible & realitively common, it's effectiveness is limited, but for CQB purposes there is still more than enough oomph out of an SBR to cause a great deal of cavitation, regardless of the absence of any fragmentation, expansion or tumbling.

Shooting a milk jug or two-liter soda bottle filled with water, make sure the cap is on tight, if it "violently explodes" on impact that is a very good visual indicator of the level of cavitation with the round in question, at a similar distance.

Plus it's a lot of fun!

[Oh Shoot]

Ran a test on some different rounds yesterday through Dolomite's chrono, comparing my 10.5" pistol with 16" rifle.

 

3 shot average:

Monarch 55gr .223:

Rifle: 2929  Pistol: 2611

Wolf WPA 55gr 223:

Rifle: 2872  Pistol: 2546

Tula 55gr .223:

Rifle: 2843  Pistol: 2612

Federal Bulk 55gr .223:

Rifle: 2840  Pistol: 2536

 

Didn't get to some other American .223 and 5.56 I had 'cause the battery died, but anyway, as expected, the short barrel lost a bit more than 300 fps, but all stayed well above speed needed for the round to do its thing on the other end.

 

I was somewhat surprised that the Monarch was the fastest overall (it's the cheap Academy Russian stuff, with lacquered case) and that the Federal brass was the slowest.

 

- OS
 

 

[Guest Lester Weevils]

Reckon the Tula is closer in velocity between rifle and pistol because it uses a faster powder, and more fully combusts in the shorter barrel? Does the Tula feel any "snappier recoil" in the pistol, compared to other brands?

 

Wonder if it would be possible to make up a custom load with lighter bullet and/or faster powder, that would minimize the difference between barrel lengths? Maybe it would be difficult to use too fast a powder and also get short barrel velocity, without over pressure?

[Oh Shoot]

Reckon the Tula is closer in velocity between rifle and pistol because it uses a faster powder, and more fully combusts in the shorter barrel? Does the Tula feel any "snappier recoil" in the pistol, compared to other brands?

Could be speed of powder burn is real factor in all this, Lester.

 

But no, I've never really noticed a diff in "feel" between anything I've shot, but could be it's there if I primed myself to really pay close attention ahead of time. The rifle is mid-length gas, so it's quite "gentle" compared to a carbine length gas rifle I also have, and the pistol is carbine length also, so feels snappier just because of that regardless of round compared to the rifle. And of course with the pistol, since the buffer tube is just rested alongside cheek rather than anchored against shoulder, it "recoils" more.
 

Wonder if it would be possible to make up a custom load with lighter bullet and/or faster powder, that would minimize the difference between barrel lengths? Maybe it would be difficult to use too fast a powder and also get short barrel velocity, without over pressure?

I don't reload, but surely there must be combos of powder/bullet  that would indeed further that, or at least a separate load to maximize the oomph from short barrel?

- OS

[RichardR]

Ran a test on some different rounds yesterday through Dolomite's chrono, comparing my 10.5" pistol with 16" rifle.

3 shot average:

Monarch 55gr .223:
Rifle: 2929 Pistol: 2611

Wolf WPA 55gr 223:
Rifle: 2872 Pistol: 2546

Tula 55gr .223:
Rifle: 2843 Pistol: 2612

Federal Bulk 55gr .223:
Rifle: 2840 Pistol: 2536

Didn't get to some other American .223 and 5.56 I had 'cause the battery died, but anyway, as expected, the short barrel lost a bit more than 300 fps, but all stayed well above speed needed for the round to do its thing on the other end.

I was somewhat surprised that the Monarch was the fastest overall (it's the cheap Academy Russian stuff, with lacquered case) and that the Federal brass was the slowest.

- OS

Interesting & informative, thanks for posting it OS, I have never personally tested Monarch, Wolf or Tula, since I don't buy or shoot those brands but it's good info to know iffin I ever come across a deal on any of them.

The results you've posted (ie: 55 grain bullet @ 2500-2600fps) by my calculations are delivering between 763 ft/lbs & 826 ft/lbs of energy at the muzzle (depending on the round) out of your 10.5" barrel.

That level of energy falls between the upper-end of the .357 magnum spectrum & the lower-end of the .44 magnum spectrum.

Now I'm going to leave it up to everyone to draw their own conclusions on whether or not that is sufficient for self/home defense use or not, but I'd say it certainly clears up many of the prior misconceptions & myths that had been floated earlier in this thread.

[Smith]

Wow! This thread stil going? This is why I like the AK Pistol ...changing the barrel doesn't matter. ;) In all seriousness good work OS.

 

If the Monarch is using the same powder as the x39 rounds the Russians use, then it is a fast burning powder. Thus the reason the barrel length doesn't matter all that much. I don't reload so I don't know if that is possible or likely but seems plausible.

[RichardR]

Wow! This thread stil going? This is why I like the AK Pistol ...changing the barrel doesn't matter. ;) In all seriousness good work OS.

If the Monarch is using the same powder as the x39 rounds the Russians use, then it is a fast burning powder. Thus the reason the barrel length doesn't matter all that much. I don't reload so I don't know if that is possible or likely but seems plausible.

Yes it is possible to use a faster burning powder, however doing so also increases chamber pressures & could be ultimately be unsafe.

Without access to proper chamber pressure testing equipment it could be done by working up charges slowly, carefully examining spent casings looking at/for signs of over-pressure but I don't recommend it, to easy for something to go wrong.

[Guest Lester Weevils]

Yes it would be interesting to know how weird one could get with fast powder versus over-pressure. I'm ignorant of it, except for instance noticing that with faster pistol powders, one must use fairly light bullets in 9mm to get good velocity. Real fast powder in 9mm is only good for light target loads using heavy bullets. Otherwise there are over-pressure problems. One has to use slower powder to load a thumping 9mm with a heavier bullet. Similarly revolver magnum rounds need pretty slow powders to get heavy thumpers without over-pressure. Granted, all the pistol powders tend to be faster than rifle powders.

 

Comparing energy vs max pressure, 44 mag vs .223-- According to the following links, .44 mag energy can range between 760 to 1500 ft-lbs with a max pressure of 36,000 PSI, and .223 can range perhaps 1100 to 1300 ft-lbs with a max pressure of 55,000 psi. But those .223 energy levels are for higher velocities than OS measured. Maybe the energy is "about equal" between a midrange .44 Mag load versus a midrange .223 fired from a pistol?

 

http://en.wikipedia.org/wiki/.44_Magnum

 

http://en.wikipedia.org/wiki/.223_Remington

 

It is comparing apples and oranges, big bullets vs small bullets etc. But because the max pressure for .223 is higher than for .44 mag, wonder if there really would be some wiggle room for a .223 "short-barrel custom round"?

[Oh Shoot]

Wow! This thread stil going? This is why I like the AK Pistol ...changing the barrel doesn't matter. ;) In all seriousness good work OS.

 

If the Monarch is using the same powder as the x39 rounds the Russians use, then it is a fast burning powder. ...

 

No idea, but the Wolf and Tula are Russian too of course. I think I read the Monarch is from Ulyanovsk, if anyone knows for sure.

 

Wolf changed its factory source about a year ago, now is adamant that it's not Tula or Herter's (which shows Tula head stamp on mine) or Ulyanovsk, so maybe it's Barnaul, who knows.

 

Every time I find a Russian headstamp visual site, seems the news ones have changed.

 

- OS

Edited May 21, 2013 by Oh Shoot

[RichardR]

I'll have to find some Russian-made 5.56x45mm & 7.62x39mm yank the bullets on them and take a look at what sort of powder they are each using.

I know that I have at least 500 rds of Wolf 7.62x39 that I bought years ago when it was on sale & never bothered to open because I was getting into AR's more seriously at the time & I still had an unGodly amount of Chinese surplus stockpiled that was the cat's meow w/regards to AK ammo.

While I hate to break open a brick just to short it one round in the interest of science what the heck, I don't really ever shoot any of my AK's hardly at all anymore anyway, maybe breaking that brick open will get me excited about shooting them again.

And maybe, just maybe I might have a couple rounds of Wolf 5.56 that are left over from an AR torture test I did about 13 or 14 years ago, which I believe I posted to either the Firingline or theHighRoad forums (or both don't recall off-hand) anyway I could have sworn that I saw a partial mag full of steel cased ammo (probably Wolf from that torture test, since that is the only time I can ever recall shooting steel cased 5.56) when I was going through a bag of old USGI magazines & noticed one was a bit heavier than it should have been.

I didn't strip the rounds out, before tossing it back into the bag so they are still in there, I haven't used USGI magazines in at least 10 years though or whenever it was when I switched over to using Magpul magazines.

And the only time I've ever used any steel cased 5.56 was for reliability testing so they'd be at least a decade old & might not be the same powder as what they are using these days.

If I recall correctly the Wolf 5.56 seemed to be a bit underpowered & not as accureate (due to inconsistancies in shot-to-shot velocities) compared to the Q3131 & M193 that I usually bought.

Anyway I'll dig through those old USGI mags tonight and see if I can find that partial magazine of those Wolf 5.56 & I know exactly where the Wolf 7.62 is, so that won't be a problem.

Like I said though neither of these are current Wolf manufacture, both of them are easily over a decade old, but I'm bored as heck today & it sounds like it might be interesting.

I'll take some pics to share, just because everyone likes looking at pictures!

Maybe someone with some newly manufactured 5.56 & 7.62 can do the same?

[yamaharacer599]

kind of off topic, but didnt want to start a new thread. my ar pistol is 9mm so its kinda irrelevant on what you guys are talking about....but

 

my only gripe with my ar pistol is aiming the thing. i started off with a laser mounted on the quad rail and now ive got some flip up sights. i can do a cheek weld on the buffer tube, but its kinda funky. thinking about going the SBR route because of this. what does everyone else use for sights?