I'm in NW Indiana. I have a pretty good idea what it is. There are arsenal markings on it. There is an alignment mark on the barrel/receiver ... And the extractor face has two holes in it, meaning that it was converted from rimfire to center-fire. All those clues indicate that it's a 11.7x56. I inherited this from my Dad, and he had Harry McGowan ( McGowan Rifle Barrels) check it for safety. They used a 45-70 round for a test round, and we've used 45-70 brass in it ever since. The brass cracks 1/2 inch from the rim after several uses... I know that the chamber dimensions at that point don't support the brass. I can make proper brass from 43 Spanish but it requires lathe work and it's expensive to buy. It would be simpler and cheaper to use 45-70 in a proper chamber.This is the little that I know,
First Priority is a chamber cast to be absolutely sure what cartridge you have.
With that you can easily figure out what cartridge it is. Way back there were many many folks out there doing conversions on rifles like that.
Ive seen brass formed for 11.7 x 56r from 45-70 and I want to say also with 348 Win, 45 Basic and 43 Spanish brass.
If it is 11.7 x 56r you might find some at places like Petersons, Quality Brass, Buffalo Brass and other brass and black powder suppliers.
Lets see what @Leadeye says.
But seriously order yourself some Cerrosafe and do a chamber cast before you buy anything that you might, Think it is.
What county do you live in?
Good Luck.I'm in NW Indiana. I have a pretty good idea what it is. There are arsenal markings on it. There is an alignment mark on the barrel/receiver ... And the extractor face has two holes in it, meaning that it was converted from rimfire to center-fire. All those clues indicate that it's a 11.7x56. I inherited this from my Dad, and he had Harry McGowan ( McGowan Rifle Barrels) check it for safety. They used a 45-70 round for a test round, and we've used 45-70 brass in it ever since. The brass cracks 1/2 inch from the rim after several uses... I know that the chamber dimensions at that point don't support the brass. I can make proper brass from 43 Spanish but it requires lathe work and it's expensive to buy. It would be simpler and cheaper to use 45-70 in a proper chamber.
I always load for trapdoor pressures, and over the counter 45-70 loads should be safe in any rolling block. The bore in this is exceptionally good (for a gun builtin 1875) with deep rifling and a few small pits. I've shot side by side with a Pedersoli sharps, shared my ammo, and had nearly identical groups..... I don't want to change the bore , just the chamber.I had a rolling block in .43 Egyptian that I was unwilling to fight the reloading game with, especially since the barrel looked like old sewer pipe anyway.
Not wanting a round that would stress that old action, I had a barrel turned and chambers for .44 SPL. It was an easy fit, and made a fun shooter that I never worried about metallurgical failure.
Who did your barrel work?I had a rolling block in .43 Egyptian that I was unwilling to fight the reloading game with, especially since the barrel looked like old sewer pipe anyway.
Not wanting a round that would stress that old action, I had a barrel turned and chambers for .44 SPL. It was an easy fit, and made a fun shooter that I never worried about metallurgical failure.
Gary Growe, Columbus, Indiana My buddy had one done also, pretty sure he used Penrod on Manchester.Who did your barrel work?
Ok. Thanks for that. It was a legitimate question, and that was an honest answer.As a gunsmith I will not nor do I know any gunsmith who will bush a chamber due to liability.