With those markings and that condition, my guess would be Egyptian.

Other markings? Remington two or three line on upper tang?

It has the early bar extractor and a shotgun butt, which is unusual on a carbine. The long eared hammer does look Egyptian or south American. Would guess built by Liege makers, but they usually cover it in proof marks. Might look under the forearm, if possible, for more proofs.

Cartridge identification... chamber cast is the way to go. Jillions of these were made in the late 1800s for use all over the world. Bore dimensional tolerances were all over the map, which does not help when trying to pin down the cartridge.