AR pistol question

[improperlyaged]

I am considering an SBR AR with an 11.5" barrel. I was wondering what would be the best defensive ammo for this barrel lenght? I would also like to know at what distance would the gun be effective with m193 or m855? I know that the 5.56 needs around 2600-2700 fps to fragment. But at what distance does this take place? What distance the does the round go below 2400 fps and start to fail to tumble?

 

[Ryanxia]

Might have better luck in the rifle section (even though its legally a pistol) rather than the NFA section. Just my opinion. Also, what length gas tube would you be using? Carbine length or pistol length?

 

[yugorpk]

You'll get 2600 FPS out of most 55 grain ammo. If you are reloading you can get a little more speed with a fast powder. I like 4198 in SBR's.

 

[improperlyaged]

It will be a carbing length gas system. I don't have access to reloading at the moment, so I am stuck with factory ammo.

 

[HRnightmare]

I use 62 Grain HP 5.56 in my "defense" mags. It functioned and worked will in testing as does 55Gr ball.

After converting my AR to a 10.5" SBR I did initially have gas problems with brass 5.56 but .223 and steel cased 5.56 would function properly. I went to an H2 buffer which solved the problem.

 

[strambo]

The best ammo for an SBR is probably the TSX line 50, 55 and 62 gr. It is hard to find and spendy, but outstanding terminal performance from barrels as short as 7.5" (the 50).

Other options are the 75-77g OTM rounds, 62g bonded SPs like the Federal Fusion, 64g Gold Dot etc. The classic M193 and M855 loadings are hit or miss in full length barrels, really iffy from SBRs. They'll kill all right, but fragmentation is a maybe.

 

[yugorpk]

If you can get yourself into some reloading gear 22 grains of H4198 with a 55 grain bullet will easily push 2700 FPS and be dead nuts reliable out of down to a 10.5" barrel. 19.5 grains of H4198 and 62 grains will push 2500 FPS and be equally as reliable. Ive shot a few thousands of rounds of both through a 10.5" primary arms upper with nothing fancy in the buffer area and its a 100% cycling gun with VERY tight groups.

Ive got some 69 grain Nosslers I need to work up for SBR use.

 

[MachIVshooter]

Not really an NFA question, but..........

Why are you concerning yourself with the performance of ball ammo? As civilians, we are not stuck using ball for defense; it is plinking ammo. For SD and accuracy, there are far better bullets and loads, including stuff that performs well from short barrels.

 

[improperlyaged]

MachIVshooter, I would like to only stockpile one or maybe two types of ammo and not worry about buying certain ammo types while on sale. I primarily have stockpiles of m193 and m855

 

[Overkill870]

I am playing around with testing some 75-77 gr otm loads for my 11.5" sbr. Not sure if they are best but they seem to have a decent following with the sbr crowd. Pretty good if you ask me: 77gr Nosler gel test

One thing I have noticed when talking sbrs online is that some people will tell you that you are sacrificing so much velocity that you might as well be shooting 22lr. This is rediculous as even m193 and m855, while not ideal, will far outperform pistol calibers. I think they spread this nonsense to reinforce their own decision not to plunk down $200 for a stamp.

 

[yugorpk]

99.9999+% of shots fired through any civi owned AR 15's don't get fired at anything that the velocity of the round makes any difference. If I'm shooting at a pig 300 yards away I am going to assume that my vision has improved to the point where I can see a pig 300 yards away and I will be suitably impressed. Otherwise I'll be using a suitable caliber hunting rifle with a big scope on it. Do I really believe I'll be shooting people with any of my AR's? Not for a second so things like terminal ballistics or bullet expansion mean nothing. Maybe I'll smack a deer at under 100 yards with a subsonic 300 BLK and try for a well placed shot. Otherwise 2500 FPS out of an SBR will put a .223 bullet out to 200 yards with minimal drop just fine . Not going to get 2500 FPS out of a .22LR. Still great for gongs and tin cans and coyotes.

 

[Tirod]

The best defensive ammo is what the DOD issue for that specific gun, the Mk18/CQBR. They buy Black Hills 77gr OTM and pay for it. It's called MK262 in the service. You can too - just save the M855 for practice. Keep the good stuff in your load out only.

The difference in performance is still incremental - but a open tip can expand down to 1800 fps. Out of a 10.5" barrel it can still retain 1,000 foot pounds of energy out to 80m, good enough for deer hunting in a lot of situations. Goes to those complainers saying it doesn't have power or won't break up reliably - don't shoot past it's effective range and don't use hard target ammo, use expanding point hunting ammo or Mk262.

Use the cheap stuff for practice - nobody is as good as they think they are, get into competitive shooting and expect disappointment the first few matches as you publicly stumble around and blow great shots. We all do. We aren't genetically "Expert," we have to practice enough to not make mistakes. That's what the top tier shooters do - practice until they can't make a mistake.

Stock up all the M855 you like, shoot the good stuff on live targets when it matters.