So every so often I like to rotate which magazines I keep loaded in the safe. Not sure if that's necessary but whatever, I do it. Just now I went to rotate them, and when I loaded (It's in .40 btw, 10 rd magazine) the rounds in to the other mag, everything was fine until the 10th round. Once I put the 10th round in, I heard something rattling around inside the mag (it sounded like a round). I put the rounds back in the other magazine. Nothing moving around. Back into the problem mag and there it is again. I take the mag apart, make sure nothing looks out of whack and it doesn't (to me). I put it back together and same problem. If I leave 9 rounds in there, I don't hear anything. Once I put the 10th round in, something is moving around. I put that mag into the gun and rack the slide until all the rounds are ejected. They all eject fine. Is this normal? Is there something wrong with my mag that I'm not seeing? Thanks guys.