I purchased one of the first M&P40 pistols that made its way into my state. Mine had the proverbial "gritty triggerpull". Even after a thousand rounds through it, the trigger was still gritty. I did not send it back to Smith & Wesson, but rather chased down the source of that gritty feel. Turns out, the stock striker block had relatively sharp radius shoulders and the machining was not as smooth as it should have been (i.e. there were tiny ridges in the finish). A warranty fix? Yep, could have been, but I chose instead to remove the striker block, chuck it in a drill, and polish a better and smoother radius in the shoulder. Reinstalled the striker block and, voila, smooth trigger. If your pistol has a trigger pull to your liking, I wouldn't mess with it. I've installed a number of Apex trigger kits in other M&P pistols, including my own M&P9 Shield, and they work as advertised. They are not necessary, especially if you like the trigger as it is now. Enjoy our M&P pistol and always remember, 'A Warm Barrel is A Happy Barrel!' So get out there and warm the barrel with some bullets downrange.