I've got 1 & they are a blast to shoot. You use the paper caps in a "cup" as ignition, pyrodex as the powder & a #4 buckshot or 22 ball as a bullet. The bullet swages down to approx 20 cal as it leaves the bore. They also made on in 36 cal & had the original 454 Casull & those little North American 22 revolvers that would fit in the palm of your hand.