Had my Bushmaster Ar at the range this a.m. Fired 20 of my reloads. 1st round in the magazine would fire then eject, but the bolt failed to pick up my next round out of the mag. Pulled the handle back, and the next round chambers, fires, ejects, but again the bolt fails to pick up the next round, even though the bolt slides into battery. I had some factory ammo on hand, fired it. The bolt picked it up, chambered it, fired it, but the fired case then hung up in the ejection port. I pulled the handle back, cleared the round. Same thing again. I had two different magazines on hand. One is an aftermarket, the other the original from Bushmaster. Same thing with both. What gives?