You learn something every day.
It is a pity there isn’t a top view of the gun but if you look carefully at the B&W link photos it would appear that the flash tube is recessed into the breach face in this particular case. It’s not too clear but if you look hard it would appear that the cartridge has an extension on the rear which matches slots in the breach face. There are also the tubes under the barrels to take a ram rod, indicating that it was probably once a muzzle loader. I can’t see anyone inserting the empty cartridge first then loading it from the muzzle.
These old guns, particularly conversions, have such an interesting tales to tell.

Last edited by Oldfarmer; 10/14/10 05:50 PM.