Dry firing will not cause any harm to most guns. There are some guns that I would not dry fire like old first generation single action armys. Basically if they were made in the very early 1900's or 1800's before good heat treating processes I would not dry fire them. Also do not dry fire rim fire guns. The firing pin is not centered and will strike the breech face and cause damage to it.

If you take your gun to a gunsmith to get work done, no matter how minor, it will get dry fired many times while he performs safety checks and such.

A shot primer does nothing to sushon the firing pin. The indentation is already there so what is the firing pin going to hit? Nothing.

Dry fire away. I dry fire all of my guns.