Need ammo? Good luck on the 11.75mm Montenegrin revolver.
However, Cartridges of the World 8th edition, by Frank C. Barnes, notes:
Bullet diameter is .445 inch.
Bullet weight varied from 282 to 313 grains.
Muzzle velocity is around 700 feet per second.
Barnes offered no reloading data, but said he'd been told that ammo could be made by shortening and reworking empty .45-70 cases.
The R with a crown over it is a common theme for proofmarks, according to the Official Guide to Gunmarks, 3rd edition, by Robert Balderson.
A crown with an R over it may indicate a Belgian proofmark for smokeless powder. Or, if the crown has a cross jutting from it, its an East German repair proofmark. Or, it's an English reproof mark from Birmingham. Or it's a German repair proofmark, circa 1891 to 1939.
Without a closeup photo of the proofmark, it's hard to say.
Even if it's been proofed for smokeless powder, I wouldn't risk life and limb shooting smokeless powder in this hoary beast. Use black powder in it, should you decide to cobble together rounds for it.
In my vast reference library, I could find no information on reloading for this caliber. I'd suggest you slug the bore and chamber mouths before ordering a bullet mould or obtaining bullets that might work.
With proper-sized cases and lead bullets, reloading with black powder would be fairly straightforward.
Most .45-caliber cast lead bullets made for muzzleloading rifles measure .445 inch or thereabouts. Perhaps one of these bullets, in the proper weight range, would work.
As Barnes said, .45-70 cases might be altered. However, I have no idea how involved this might be.
It's probably best left as a wall-hanger. If you do decide to fire it, have it checked by a gunsmith first. Tiny hairline cracks and other faults in aging metal are hard to spot. Even a trained eye can find it difficult.
It's an interesting revolver. I wonder what its story is?
