There were sent to me some time ago (sry I cannot remember who send them to me but I did post them on this forum. I think they were both 1884 versions with the .446" groove diameter.
if so, they may have the bolt with 2 locking lugs, that the Model 71 of 1876 didn't have.

The 20" bl. carbine I have, is marked Mod.71 on the left side, then 1876 on the right side of the action. It is a single shot, single locking lug. Also, the action is octagonal as-is the forward section of the barrel, over the chamber.

The ctg. pictured with this rifle below, is the .450 Alaskan, the wildcat ctg. I re-chambered my rifle to, in order to obtain good brass and to use a .457" bullet that fit the oversized groove diameters in these rifles.