AR pistol question

[AJ C-burg]

I'm assembling a 556 pistol and would like some opinions.

I already have a complete billet lower with a Spikes pistol buffer tube and ST-T2 buffer. My original plans were to go with Seekins billet upper and rail, BCM CHF 11.5" barrel Mod 4 CH and gas block, and DD BCG.
I've been contemplating going 7.5" the past few days. I was looking at the Phase5 barrel and their pig tail gas tube. Or instead of pig tail get an adjustable gas block. I'm worried about a 7.5" being reliable and accurate(-300m not driving tacks but on target).
What are your thoughts?
(I shoot 62grn ss109 reloads or PMC XTAC)

[Zet70]

It's generally accepted that 11.5" is the shortest you can reliably run with minimal tweaking. That being said, it can be done but don't be surprised with short stroking and gas system tweaking. Nevermind the velocity loss.

[AJ C-burg]

Thanks Zet. I'm going to go with the 11.5" barrel. Maybe later down the road I'll try a 7.5".

[mythaeus]

A little late to the party, but other than the initial problem with gas leak due to poor job of installing the gas block on my 7.5" DPMS kittykat barrel, I had zero problem with reliability. I don't really take it out for long range so can't speak to long range accuracy, but I'm quite happy with my pistol overall. I think 7.5" makes it more like a pistol, especially in term of balance, vs. 11.5", which would tip it front heavy.

Oh, I generally stay away from fancy parts, like pig tail gas tube. Not sure why that's necessary.

Al

[Dochartaigh]

11.5" is also right at the cusp of the minimum FPS needed for .223 bullets to fragment on impact (i.e. to do the most damage).

Even 10.5" is a little below that ideal FPS (which is why BCM doesn't make a barrel less than 11.5"); 7.5" is definitely way under.

[Karys]

The CMMG 7.5" upper on my pistol runs fine with a normal gas tube. The only issues I've had was due to operator error when I assembled the LPK incorrectly. It's run like a champ since getting the lower right.

[Normlizer]

I have a 7.5" dpms kitty kat upper. Runs like a champ always a head turner at the range. Don't forget ear plugs they seem to be alot louder than your reg 16" ar

[ungawa]

11.5" is also right at the cusp of the minimum FPS needed for .223 bullets to fragment on impact (i.e. to do the most damage).

Even 10.5" is a little below that ideal FPS (which is why BCM doesn't make a barrel less than 11.5"); 7.5" is definitely way under.

I agree, BUT - If you want it as a toy, buy it. If you need to use it for self-defense, you can load it with bonded soft points or TSX and it will still kick serious ass. SPs have been known to foul up feed ramps on some ARs after hundreds of rounds, but I doubt anybody will fire hundreds of rounds in SD. Point is, you have options, look into them.

Even with ball ammo - It's better than a P90 or a FiveSeven, and I hear they can kill (if not ideal).

[AJ C-burg]

Thanks for all of the info. I want this to be one of those "Jack of all trades" kind of assemblies. So far I'm set on the BCM 11.5" barrel. I might do a 7.5" after I finish a few other projects. Any suggestions besides BCM for the barrel? I looked at the FN barrel from Spikes but that's a 12 month backorder.

[340M&P]

Kitty Kat 7.5 flattop upper on Palmetto lower. All standard parts other than that. No jams, no issues since day 1. About 500 rounds so far (only a couple months old) and as for accuracy, head shots at 50 yards, body at 100 yards. Put a red dot on it and my accuracy improved.
25" overall length, flame throwing beast!
Enjoy