Sounds like a Frank Wesson Pocket Rifle. Flayderman's will give you some details so that you can determine which model you have. There are three frame sizes and three types in each frame size, all rimfire - .22, .32, .38, .44. Charming little guns. You can make up low powered loads with .22 case primers that should work in the gun, but the action is quite weak, so they have to be cat sneeze type loads. Frank Wesson made nice guns. If yours is a .25 RF, it has been rebored, and .25 Stevens can be made according to an article in the June 2010 SSE. Have fun.