While the majority of the grittiness in an new factory M&P trigger pull is caused by rough machining/stamping of parts and channels, anywhere metal touches metal in the fire control system will stack negative friction tolerances. Some triggers come better than others.
If your local gun store has more than one gun for you to try, even dry firing, do so. In pulling a trigger slowly you will discover the best of the lot. It may be good enough to let dry firing of a few hundred rounds smooth and lighten it, at the additional cost of a gradually, inconsistent evolving gun.
I use a Dremel hispeed rotary tool and have for years. Never wrecked a part. Just go slowly. Felt tip, jewelers ruoge.
I polish the whole trigger bar, everywhere. It onl takes a minute. The RDS trigger bar interfaces with numerous surfaces in the gun, so I polish them all.
The striker BLOCK (safety) gets a lot of attention, as does its channel which is always rough and has machining burns at each end.
The trigger bar interface with the sear has a specific geometry for proper release. Polishing this area incorrectly and changing precise angles will produce a less desirable trigger, but polishing the trigger bar sear mating surface is helpful.
My first Shield five years ago, the only one left in the store, had a gritty pull that punched in about 9# on a digital gauge. Polishing components made it a much smoother, more consistently controllable trigger that broke at 7#, better, but still to heavy for quick shooting with accuracy for me.
So I ordered an Apex kit, installed it myself and immediately improved the feel of the gun for me.
The factory could take a little extra time to polish and fit parts, but since the average shooter doesn't demand it and the rough gun still sells, they save manufacturer time and costs.
I do hand polish many parts with wet/dry sandpaper. Used properly, the Dremel will do as good or better a job of polishing in less time. As with any power tool, one could overuse it quickly, but a measured, considered approach will yield great results.
and dry fired their gun a lot. Toothpaste is a mild abrasive, so should remove burrs, etc. Has anyone ever tried this, and what was your experience, especially with revolvers? Inquiring minds want to know!
