Really short unsurpressed 5.56 ARs give you a flash-bang with every round. And then there is the reduced velocity. 300BLK much better round for short barreled AR pistols.
Nothing too special here, but they work well and they are mine. Suppressor mounts of both of course, along with a number of other parts I made myself.
9" 300 Blk with LAW folder, I drop it in a backpack to go places:
Are we including SBRs here? 12.5" 6.5 Grendel with a barrel I machined from a blank. It made some really good hits on steel at 600 yards this weekend, and was more consistent in the wind than my 16" 5.56, hard to argue with that: