I saw the "Wild West Tech" program on The History Channel, too. As I recall, they said that the deputy Sheriff who was guarding "Billy the Kid" when he was arrested awaiting trial loaded a stack of dimes in the 12 guage side by side shotgun instead of buckshot. Supposedly, when "Billy" shot the other deputy while escaping, he then greeted the shotgun's owner with a "howdy" as he walked back from across the street and shot him with his own shotgun left in the room they had been holding the prisoner.

I think it was Mythbusters that tried this remotely, because as said this could also potentially blowup in a person's face, if the dimes got wedged in the barrel as exiting. The dimes came out in that test, but they were very ineffective barely penetrating whatever target (pig carcass or something) they shot it at.

Kids, DON'T TRY THIS AT HOME!!