Fin:

The were designed to be used with .22 shot cartridges. I know my father had a few at one point. Don't remember the weight of the shot charge (not much, as you might guess), but it was supposedly No. 12 shot. The ones dad owned were in a case about the same overall length as a .22 cartridge, including the bullet, and were crimped at the mouth of the case. I think he used them to shoot rats in a neighboring farmer's barn.

Rem