I presently have 4 M&P's. 40, 9, 45 anmd 45C. On everyone of them when I insert a fresh loaded magazine the slide releases without me pressing on the slide lock. It seems to automatically release. Is this as designed or a flaw in the design. I am extremely satisfied with my M&P's. The M&P 40 is our department issue weapon. We went to it from the Beretta 96 and Glock 22. My next purchase will be the M&P Pro 9MM with the longer slide.