So my uncle just purchased a (what he calls) M&P9 long slide, 5" barrel. (I have no connection to this weapon what so ever) The problem is when he inserts a mag the gun goes into battery. It doesnt happen all the time. He's been testing it with snap caps and no fingers touching the slide release. Slide still drops. A S&W armorer told him its normal and to expect it. I called BS. Hes starting to get into competition and cant have things like this happen. Ive got emails between him and S&W which ill post at the appropriate times. They told him that when the mag is inserted with enough force the slide stop will "jump" and go into battery. I call BS. I feel its a weapon malfunction. Im about %100 sure hes not slamming that mag as hard as i do when im in the heat of competition. My XDM has NEVER done that. Can someone help us?