Originally Posted by MacCool

Nice. I have an M&P 9L with Apex DCAEK. An amazing trigger improvement. I like the M&P line a lot. Note that they're currently on sale at Palmetto State Armory, most of the models (if left in stock) for over $100 off.

Be aware that there are some reported accuracy problems with the FS and long-slide M&Ps. Thought to possibly be mis-timing of the locking block causing the barrel to lock up inconsistently. The symptoms show up at 25 yard shooting. One ought to be able to hold a combat handgun shot from sandbags or other rest and get 3 inch groups at that distance. Affected M&Ps will typically shoot 6 inch groups. One looming solution (so far) has been adding a Storm Lake barrel that's hand fitted. Cost is about $200 including the hand fitting. The other solution is still in the works - a revised locking block from Apex Tactical. Early testing has consistently shown either of these solutions to make the gun capable of 1 inch groups from 25 yards.

One could easily shrug this off as being one of the vagaries of a combat handgun. I mean, who cares if it shoots 6 inch groups at 25 yards? Most people will rarely shoot if farther away than 10 yards. OTOH, I like a nice accurate handgun. Fortunately, my M&P doesn't appear to be affected as I am able to shoot sub-3-inch groups with it, but YMMV.