Got a new ar15 9mm with a 4.5 inch barrel. I was thinking of putting a binary trigger on it but was conserned shooting that fast would cause problems with the coating. So I went out back yesterday with 9 30 round mags loaded. Dumped them as fast as I could pull the trigger and reload and do it again. After 270 rounds I pulled the bolt and looked down the barrel and it was whistle clean. Did attract some attention though. two of my neighbors came over so see if the Russians had attacked. We ended up shooting another 4 mags not so quickly (they did) and it still looked great. so 390 rounds it didn't miss a beat or even need a wet patch put through it.