owners manual

http://www.smith-wesson.com/wcsstore...03-15-2012.pdf

Yes,

The slide should lock open on empty, make sure that your thumb or hands etc. aren't preventing the slide lock from doing it's job. It's easy to get a thumb over it while shooting and preventing it from rising to lock the slide.

Could be the magazine so check several first....JJ

Sure is.

Clean your magazine(s). M&P's dispel a fair amount of burnt powder residue into the magazine. You'll see this with the dirty follower after a session on the range. Some of this debris gets into the magazine body. I clean mine after every range session. It's simple, takes maybe 3+ minutes at best, and works. I also spray a quality silicone spray (CRC Heavy Duty) into the body to aid in the free movement of the spring and follower.

Also, field strip your gun and check the movement of the slide stop. It should be smooth and unencumbered. Keep it clean as well.