When I was a young deputy I was cleaning my revolver (A Colt with a free floating fireing pin) one day just before time to leave for work. I closed the cylinder, pulled the trigger and the fireing pin broke off and flew out the end of the barrel. It was time to walk out the door to work and it was the only hand gun I had. I reported in with a loaded but in-operable firearm.
When I went on the road I drove straight to a gun shop. He didn't have a new pin, but he kindly loaned me a gun until mine was fixed. Since then, if I don't have snap caps in the right calibre I double check them and put spent casings in to dry fire.