My first gun was a GP100. On the day I bought that gun I also bought Snap Caps for it so I could practice with it at home. I never fire the GP100 without either snap caps in it or real ammo at the range. Now I have a Mark II and I was told to absolutely never dry fire it. Do I need to buy Snap Caps for this gun? And I don't understand how Snap Caps work in a semi-auto. Do they eject out and you have to refill the mag every ten shots? With the revolver, they just keep going around and around. No need to refill. Also, I do believe someone once posted how to make your own 'dry fire snap caps' with spent casings. Is there a way for me to do that with my .22? Thanks for any input or information you can share with me.