I've only had my freshly built AR to the range twice but each time I was having issues with rounds feeding into the chamber. Seems the bolt is just skimming over top the rounds. However, I can use the charging handle to rack them in. But then the case is ejected and the bolt skims over the next round resulting in that ever so disappointing "click". It go to the point where I could feel and hear a difference. On a few rare occasions it fed just fine. Should I be looking into a different mag? I'm just using a steel 20rd Bushmaster mag right now.