I own an M&P 15 Sport which has performed flawlessly except one issue: I notice that with a closed bolt, sometimes my magazine fails to snap in. Through OCD experimenting methods, I have determined the cause to be the second round in the magazine is tilted up slightly. I can reproduce the problem 100% of the time whether I have 20 rds loaded or 30. Evidently, when the second round is slightly upward, it prevents the top round from dropping down and allowing the mag to snap into the lower. Problem happens with the factory provided Pmag 30 and a DPMS 30 mag I bought when I got the gun. Does anyone else have this issue with AR mags?