Something to think about when getting an AR that uses high capacity pistol magazines. Those magazines are kinda fragile when sticking out the bottom of the mag well. Take a dive to prone position and whack the mag on the ground and the floor plat is going to come off, and you're likely to kill the mag. That's why SMG magazines are made so robust. The Colt 9mm magazine really is the best one out there for 9mm AR's.
