In the early 1970's a neighbor brought me his great grandpa's m/l rifle to redo. It was from far southern Illinois along the river. It had a back action percussion lock , single trigger , brass parts , and the gun barrel was tapered at the muzzle from 1 1/16" and 8" down to 1" straight for the remainder of the 40" .. The barrel was currently of around 45 caliber , and showed evidence of being swapped end for end looking at the barrel hangers. Obviously , it was cut and rebreached at least once to put newer rifling at the muzzle. Barrel went to be rerifled to next size up. The stock was in poor shape showing wide nonfixable spiral separations in the fore stock , and a broken wrist . Neighbor insisted on a new stock , and so we were on.....
Last time neighbor's son called me , the rifle was still shootin' and in Texas. Hope this helps somehow.. oldwood