Daryl, I am not sure that I understand the process then. Where did the flats come from? Since they have proof marks where are the barrels that were proofed?
I thought that I understood the process where flats were soldered, braised or welded onto muzzle loader barrels to convert to breech loading, but where would the proof marks come from if not from a breech loading gun? Or were the barrels re-proofed after the flats were soldered on?

Great-Great Grandson of D.M. Lefever
www.lefevercollectors.com