There's a simple, two-part answer to the age-old question: “Is it safe to dry fire my gun?” Yes. And no.
Sorry, folks. There is no one-size-fits-all answer. You can dry fire some guns thousands of times with no damage. With others, one dry fire could send a firing pin flying down the barrel.
The good news is that nearly all modern rifles, handguns and shotguns can be safely dry fired. The bad news is that even these can break or wear unduly. And how do you define “nearly all”?
Shooters just want a straight answer. “Can I dry fire my Winchester Model 70 without fear of anything breaking? How about my Smith & Wesson AR or Mossberg M500 shotgun?”
Your local gunsmith or I could tell you to dry fire away because we've never seen nor heard of such practice damaging the brand and model of rifle you specify, but there's always the first time. Heck, I wouldn't even tell you it's perfectly safe to live fire your gun because I don't know:
1. How well maintained the gun is.
2. If the barrel is plugged by a wasp nest.
3. If you're using the correct cartridges.
4. If you're using handloads with double doses of pistol powder.
I can guarantee this about dry firing: It will make you a better shot. Champion target shooters dry fire regularly. It teaches trigger control, indoors and inexpensively. Keep a safe, unloaded rifle beside the TV easy chair and dry fire during commercials. No flinching. Just finding a target in the scope, dry firing and cycling builds muscle memory and makes rifle handling as automatic as forking pie into your mouth. Smart shooters want to dry fire.
You won't destroy a gun if you dry fire it, but you could damage or break the firing pin. The pin is designed to slam against a yielding metal primer; without it, the pin will bash against an unyielding metal rim or bushing within the action or bolt body. Rimfire firing pins strike the edge of the breech/chamber. This is supposed to break rimfire firing pins or severely gall the breech, yet an experiment conducted by Jeff Johnston of the NRA showed that 1,000 dry fires in a Henry pump-action .22 LR and a Browning Buck Mark II pistol resulted in no visible damage to either's firing pin, slight marring of the breech face in the Henry and no marring of the Browning from the firing pin. The Browning's extractor did wear its chamber slightly. No subsequent firing malfunctions (through 500 rounds) resulted from the dry firing.
But again, these were just two rifles. Who's to say a Marlin, Savage, Ruger, Kimber or any other firearm will match that?
Fortunately, there are two simple, cheap solutions to the dry-firing dilemma: Ask the manufacturer if it's safe to dry fire your gun, or use snap caps.
Some gun makers will tell you to dry fire at will, while others will hedge their bets and say to use snap caps. So just get the snap caps ($1-$22) and be done with it. Snap caps are fake cartridges that absorb firing-pin energy. They make dry firing more realistic by maintaining the feel and function of ammunition cycling through your firearm.
You can get snap caps right here from Brownell's, right here from Cabela's, or right here at Midway USA.