Just to be clear, it happens with the 11, but not the 13, but the point is the same. I did buy a second 11 round mag and it does the same thing. After I did that, SA requested I send the gun and mag to them to check it. They did and returned it after a few weeks, but said nothing and haven't replied to my emails since. It actually worked great for an afternoon, then went back to doing the same. I've figured out shortly after I got it back from SA, as the slide cycles, it is dragging the round below the one being pulled into the chamber and dragging it forward just enough to cause the mag not to fall if I need to drop it for whatever reason. It does this down to about 5 rounds left in the mag, then it's fine. I don't have a ton of guns, just under 10 let's say. A few different brands, Glock, S&W, Walther, Sig, and not one of any of them does this at all ever. So it seems this particular gun is wound a bit tight. lol. Weird that it only happens with the 11 though. I haven't seen or heard of anyone else with this issue but the kinds of tolerances these guns have, especially this size with this number of rounds, it's not too surprising I guess. It does seem to be getting better the more I shoot it so maybe this is an issue that fixes itself as it breaks in.