[Dog427435]

Had the same thing happen to a 10th grade friend.
Decided to build a bomb to blow up a raccoon lair in his back yard.
He took a couple of boxes of 22 's and popped the tops off and emptied the powder into an expended CO2 cartridge.
Wanting to finish later he decided to cap the cartridge so the powder would stay dry.
You guessed it, he carefully tapped an unexpended 22 shell into the opening while holding the cartridge against his leg. One tap on the rim fire cartridge and he blew the last two fingers off his left hand from the knuckle down and a hole in the refrigerator across from him big enough to get a beer out of!
In the politically incorrect way of the sixties one of the older guys down at the gas station named him Three Finger Brown after a early 1900's ball player. He is still referred to by that nickname today.