I was under the impression that as long as your gun isn't a rimfire dry fire doesn't hurt it, no matter how many times it's done. But apparently there is disagreement on that, or no one would be talking about snap caps. You'd think the gun community would know for certain one way or the other by now. All I know is I've dry fired my Glocks hundreds and probably thousands of times and they still work. Any old experienced gunsmith or gun engineer out there who knows one way or the other?
The answer is: For most guns, to most levels of dryfire, it is completely harmless to practice.
That being said---I know three people directly (and more indirectly) that have had to return slides to Glock due to
significant amounts of dryfire over time cracking the breechface.
Other pistols will demonstrate similar issues.
However, it took
tens of thousands of dryfire reps to cause this to happen. If you dryfire 10 minutes a day for a year, you should be using a snap-cap.
If you dryfire once every couple of months, chances are it will cause no problems.
But of course, since you ARE dryfiring daily (at least 5 minutes a day, right?) you should probably use a snap-cap.
Example:
Bottom line is that dropping the hammer on a modern weapon isn't a big deal. If you are going to do good dryfire practice, however, a snap-cap is a good plan.
Fly, I'd suggest just buying spring-loaded snap-caps. (My biggest pet peeve of snap-caps for Glocks is that you then practice only partial slide-racking to reset the trigger, which is a bad idea. Unless you have a whole mag full and you rack out all of them then reload them for the next set of 17 trigger pulls, which wastes a LOT of time...) I made a bunch of dummy rounds with silicon in the primer pocket, but I don't really think that is enough resistance to protect from eventual damage. So, actual snap-caps for me.