my take on this issue is if the gun won't shoot different kinds of ammo, it is not a gun worth having. My instructions for my dpms ar says not to use steel case but i have ran almost 200 hundred rounds through it with no problems. Just clean it when you get home and you should be good to go. Like I said before if it doesn't run on different kinds of ammo, the gun in my opinion is worthless and time to trade in for something else.