I have an M&P 40 with about 800 rounds through it. The last couple trips to the range I have had the slide lock back with rounds still in the magazine. This has happened with both magazines I have. I clean thoroughly after each range trip including the lips of the magazine. What else should I be looking for? I know limp wristing will cause this and if I shoot one handed the slide locks back almost every time. I suppose it could be related to limp wristing the occasional shot. What other things should I look at?