At the Navy force protection school I went to, they taught some basics of marksmanship, and had a technique to verify proper trigger pull that involved dry firing. We all laid down on the firing line, and one instructor went down the line, placing a quarter on top of the flash suppressor. Then, after we had balanced it for a bit, another instructor would come by and you'd squeeze the trigger. If the quarter fell, it meant you were flinching or jerking the trigger. We also did it with M9's. Just check your manual to see if it's recommended or not. Some are good to go, others need snap caps. As far as 22's go, both of my 22's (Ruger 22/45 pistol and 10/22 rifle) require you to dry-fire in order to decock the firearm. I presume also that pistols like Glock, which require a dry fire for disassembly, must be fine as well.