AR9 & AR556 both in Pistol version, pros/cons, why & why not?

Quote:

Originally Posted by Circle_10

How's the reliability of a 9mm AR pistol/SBR, either Glock mag or Colt mag pattern, compare to a conventional gas operated AR type rifle?

I have a 10.3" AR SBR and have become somewhat interested in the notion of having a 9mm one of the same size and more or less same configuration as the 5.56.

Blowback pistol carbines have been generally as reliable as gas guns in my AR stable, two 9mms Glock pattern vs. four 5.56.

Gas guns seem to be a bit more sensitive to underpowered ammo (looking at you steel case Wolf), even if unusual. I was surprised how little the blowback guns were affected by lighter loads.

However, dirtying up the guns cause more issues with 9mm blowback. I have approximately ten year old LWD lower and JSE upper that starts slowing down around 500 rounds. It has always been a range gun, so not too much concern in rather frequently cleaning.

Of course the recoil impulse is different but sufficiently similar for trainers. I also had the fun S&W 15-22 AR, but there was almost no recoil discernible in .22LR. For a bit more cost per round, I usually chose 9mm.