Hello
It sounds like you have a S&W K-Frame Hand eject. The true serial number will allow you to see what series you have. You must remember there was a ton of K-Frame models that shared the same range of serial numbers, and some were different models as well, so it can be confusing attempting to find out what series you have. The Cartridge was Winchester Western 32-20 or W.C.F. Which meant Winchester Center Fire and common back when they also had this cartridge for Lever action rifles. I would Caution you on firing Modern ammo until it is determined what series this revolver is. The early ones were designed to fire Black Powder, and did not have a Heat treated cylinder. if you roll the revolver on it's back and swing open the cylinder, you can see a Place ground into the top strap to allow excessive black Powder a place to accumulate.. If that was not there, the cylinder would Bind up from all the Burned Black Powder residue which formed around the forcing cone area, and the face of the cylinder from firing it. Depending on the series this hand eject came from, I had one that was from the Forth series, That did have a heat treated cylinder and was safe to fire Modern smokless Powder ammo. Never fire ammo intended for Rifles as this had a higher Pressure than revolver's could Handle. If you would Like to P.M. me the Partial serial number of this revolver, and feel free to leave off the last digit for security reasons, I would be happy to Look up what series you have, in my reference books and get a rough idea of the year it was made for you, and whether or not it may be safe to fire Modern ammo. I also would have a competent Gun Smith Lok at it, Before firing it to make certain it is safe to fire. I hope this helps, Hammerdown