Adaptations of the Scandinavian-Siberian snaplock mechanism to percussion ignition. It might be possible to narrow down the origin of the unknown one based on the way the spring pushes up instead of down on the hammer - there were regional variations in the way this was accomplished, but but I don't know what they were.
There doesn't seem to be much on Scandinavian and Siberian-Russian weapons in English. This is a pity, because as far as I can tell these areas were one of the few places on the Eurasian continent that rural common folks could hunt and trap for fun and subsistence, so these guns, despite the very different design, filled much the same roles as did the longrifle over here.