I remember telling Larry Brown a while back when he mentioned using snap caps to check a gun at Cabala's.......I like to use a snap cap, too when I buy a gun, but I put a piece of masking tape over the primers when I check it. It will tell you a lot more about the firing pins than if you don't. I don't know if anyone else does that or not, but it always works for me. It says a lot when you look at the primer indentations in the tape.