Hi Evgeny.
Just when I think I've seen most everything in Ethno firearms, something new pops up.
This is a tough one to pinpoint it's original origin. At first glance at the muzzle end, it says Indian Torador. And I'm convinced it did start life as a Torador barrel. The front sight even mounted on the top edge as typical Torador.
But the breech end of the barrel looks nothing like Torador construction. There is no swell at the breech, and there is an actual breech "plug and tang" which is probably threaded into the barrel. Torador barrels were flat at the breech end. The breeches were plugged by forge wlding (or similar). And the breech plug on this barrel, with it's slight curve downward, looks Europen in origin.
So, I'm going to say this barrel started life as made for an Indian Torador long gun. Later, back in the period, it was cut off at the brech end a genuine breech plug added, and converted to percussion with the addition of a drum and nipple as shown. There may have been breech damage to the barrel, thus the cut off and conversion. Even the rear sight slot looks exactly like the ones on Torador barrels. Could have been cut off and re-welded to the barrel.
Of course, I'm just speculating. It could be an Ottoman made barrel, with a Torador style muzzle, and converted to percussion. But I don't think so. For now, I'll stick with my first guess.
Rick.