Looks like a commercial Reichsrevolver knockoff. The reason I'd say that is the hole above the grip looks like an RR with the safety lever removed.
I've a similar unit with the half round bbl with almost no markings. The ejector on mine is marked Tranter Pat. It has a crown over 8 marking on the cylinder and bbl and no others at all.
Yours has the steeple type fluting like an RR too
Try 44 Russian in the chamber
Built like a tank too.