i was looking over my m&p and found that the slide can easily be moved left to right on the front end. you just grab it and move it left to right slightly and it does make a rattle. i would like to know from other m&p owners if this is natural or not.
heres a video for some visuals of what im talking about.
http://www.youtube.com/watch?v=_DuOjKReAIk