I can just see those b**ches chasing their balls around ducking for incoming...
5.56 subs can be finicky little bastards without some modifications to the gas system...SOMETIMES an adjustable gas block will do it, but you have to make adjustments with a can on vs. off... may even need to enlarge the gas port in the barrel to get them to function properly. Not positive on piston driven systems, I've only fooled around with DI gas systems. That's the great thing about .300 AAC - they just flat out work, no matter barrel length or gas system type, canned or not.
I've shot 300 subs through a can in an indoor range. It was surprising how quiet even in a narrow (2 lane) range it was. Even the 5.56 supers through a can didn't make my ears ring. Wouldn't recommend it be done on the regular, but...it wasn't deafening by any means.
I SO want to build an AR for myself, but wifey sees AR, she sees "assault rifle"... Me: 
So...I just play with them at work. 
