I shoot USPSA Matchs looking at getting a M&P Pro Series 9mm a guy at my local club told me that his on the first day out of the box would not go to slide lock then when it did would not release from slide lock. any one out there have this problem and if so was it a easy fix just want to know before i spend money or i'll just stick with my Springfield

I'm also looking at getting a model 29 any advice on this gun? (Dirty Harry's model right?)

Mine took a couple hunderd rounds before it would lock back on a empty mag every time. Never heard of one that couldn't be released with the slide lock.

Trouble with the slide lock might be caused by the
magazine follower. Can't see the pistol from here,
but there's likely a recessed lip on the mag follower
that presses upward on the slide lock mechanism,
after the last round is fired.

You can see how it operates by looking inside the chamber
while inserting an empty magazine. Sometimes you can
'tweak' the follower lip to make it engage the slide
lock better. Takes patience to get it right, though...

The M&P series is good. But rest assured I also have the Springfield XD service 45 ACP with 2 13 round mags, you can't go wrong at all with that gun.

Model 29 was Harold Francis "Dirty Harry" Callahan's weapon of choice.
Be sure and get a DVD of the movie....it's still a cool view !
Gary