15, never cleaned it, just a shot of WD-40 every 600 rds. He had 20 30 rd mags, and a kid to load them with stripper clips. They were Harry's reloads, knocked out on his Star Progessive, (IIRC) I know he had a Star, but he might have used something else to load the 223's. I believe that he told me he used Ball C powder. I've shot thousands of rounds thru AR's, and never had a problem, except for a couple of failures to close the bolt, on brand new guns, 1-2 each, on a couple of guns. All closed instantly with a tap on the bolt forward assist. It was just "new gun" tightness-machine marks. those who claim that the AR has to be kept spotless, is malfunction-prone, etc, are just fos, that's all.