I'm planning my first .500 3" soon(the Lancaster was a consignment). Rebuilding an SR Jeffery Jones under-lever single. It started out life as a .58 caliber percussion rifle, then converted to centerfire at a later date. I am going to build an ovate barrel for it. The muzzleloader conversions really appeal to me. Likely because of the amount of work involved and these conversions were only undertaken on high quality guns.