that depends on the number of times you dry fire it- if you're racking it a lot, it's gonna show- however, snap caps are never a bad idea- if it's infrequent, say only to lower the hammer( which you can do without banging the firing pin) after cleaning or such, then no, not necessary- i've been shooting over 30 years and the only damage i've ever seen is on 22 rim from dry firing- burr in the chamber