I need to do the same thing with my new M&P's. I would think that dry firing with snap caps would be perfectly fine as this is exactly what they are for. Safely breaking in that trigger and practicing trigger sqeeze and control through dry firing. Dry firing extensively without snap caps is a no no on certain firearms but I don't know about the M&P specifically. I plan to do it on mine with the snaps/dummy rounds in place. YMMV.

Most modern pistols are safe to dry fire in practice.
Nevertheless, I strongly suggest the use of snap-caps anyway. They're cheap insurance.

Whenever you practice with snap-caps, make really, really sure that there is no live ammunition anywhere nearby. All it takes is one mistake.

Originally Posted by Steve M1911A1

Most modern pistols are safe to dry fire in practice.
Nevertheless, I strongly suggest the use of snap-caps anyway. They're cheap insurance.

Whenever you practice with snap-caps, make really, really sure that there is no live ammunition anywhere nearby. All it takes is one mistake.

Agree with every word. I got some A Zoom's when I bought my 9mm. Work as you'd expect and they are cheap.

As for the 'no live ammo nearby', I don't even have any in the same room.

edit: http://cgi.ebay.com/NEW-A-ZOOM-PRECI...item45f91c5a79

Another method is to use those small rubber ear plugs placed between the hammer and the firing pin/transfer bar. I use that mostly, and only the snap caps when wanting a more realistic feel to dry firing. Of course that won't work on a striker. I have read somewhere about dry firing a particular striker pistol that the mag had to be done a little differently due to a lever rubbing when the mag was out, or something like that. Can't remember the details.

Also, I never have live ammo in the same room.

I ordered Pachmayr snap caps along with some defense ammo and got it yesterday for my MP40. The caps have a brass base and a plastic body that is tough enough to withstand loading into a magazine, chambering and ejecting without getting torn up. I began to realize as I first loaded a magazine with the real stuff and set it aside and then loaded another one with the blue and gold snap caps that it was very dangerous having the two magazines within reach. I quickly put the real stuff away so I could concentrate on practice firing. I ran the five caps through the gun at least 6 times. It gives you plenty of practice racking the slide. But I could concentrate on the sights through the trigger pull and could fine tune my finger motion to minimize sight movement. That is good practice that I will be repeating every few days.

I was taught that dry-firing center fire firearms is harmless to the gun and that the only firearms not to dry-fire without the use of snap caps are rim fire guns because the firing pins make contact with edge of the chamber. Have I been misguided? I hope not because I do a lot of dry firing with my guns.

I've never been able to imagine dry firing a firearm to have any negative effect on the weapon. It goes through with and was intended for so much more stress in so many different ways during live fire.