I have a lang which was converted from pinfire to center fire. A couple years ago I came across a WRichards which was a muzzleloader converted to center fire and a pinfire which was converted to center fire by Manson a cleaver block added to the rear of the action that held the firing pins. Barrels had been shortened about 3/4” and rechambered. Must have worked because it pass proof twice. Good barrels were repurposed instead of being scrapped. And labor was cheap.