Just built my first AR, took it to the range and had 0 issues. 100+ rounds without any sign of trouble. Put it back in the case, went to the range again and on almost every round had feeding issues. First sign of trouble was that I had to beat the bottom of the mag to get it to lock in and mag release is real tight. Then I'd charge it, first round would go but every round after that would only move slightly forward and get scraped up by the bcg. Manually charging it loads the round ok, but thats about it. The second range time I was using steel instead of brass, but messing with it at home with brass it seemed to have the same issues, not feeding quite right, tight mag fit and tight release. Without the upper connected the lower seems to lock in mags just fine. An unloaded mag locks in easier than loaded and with the bcg held back the mag also goes in easier. Still a little tight with the bcg back and with an unloaded mag. Any help/suggestions would be greatly appreciated.