Hey guys, earlier tonight I was doing drills, because, thats what I do when I got too much time. I normally use expanded shell casings in the magazine when I do dills, aside from assembly/disassembly, so that the gun cycles normally as it would with a live round (besides bad feeds that happen). But today while I was running clear malfunction and transition drills I did it with out a casing in the mag and the rifle still cycled as if there were rounds in the magazine. I took it out back to a berm and cycled it about 40 times with live rounds and got about 5 failure to feed malfunctions, a couple failure to extract, and a couple double feeds . Before now, I fired about a total of 130 rounds through the rifle and didnt have a single problem. What can be the issue? Im kind of at a loss because I took the weapon apart and assembled it same as I did before for cleaning but something just seems wrong when it cycles. Hopefully its my error any ideas?