I should also add that in all of my .223 / 5.56 MM AR-15's, Mag-Pul P-Mags are all I now run. I probably have well over 30 of them. In .223 I'm starting to like the 20 round models more than the 30 round P-Mags because they offer less interference when shooting off a rest on a bench. I generally don't shoot more than a 10 shot string slow fire. That doesn't heat up the barrel to the point that I can't hold my hand on it. The P-Mags have never given me a single issue. As far as AR-15 magazines, they have pretty much become the standard all other magazines are judged by.