I picked up my M&P FS 9mm two weeks ago (first time gun owner). I did a very basic cleaning/lube of the weapon when I took possession of it (bore snake with a few drops of CLP on the "knot", and lube on the slide points/rail). I have run 500 rounds through it, 100 rounds of each of the following ammo; WWB, American Eagle, Remi UMC, PMC *and* Sellior and Bellot (all 115 grain FMJ). The gun has worked flawlessly with every brand of ammo I've tried.