RJW-

May I see the rest of the barrel flats and the breech end of the chambers too please?
are there any other markings at all on the action (including forend iron etc) and barrels?
I'd also like to see the muzzles and front sight.

The rim cuts will certainly be slight.
There wasn't much rim on the rifle and gun cartridges, and the rim treatment isn't what we're used to seeing on our modern cartridge guns and rifles.

Cheers
Tinker