The gun would have to have a bit of a history, if it is indeed from the between-the-wars period and brought back by a GI in 45. It was common for Soviet guns to be brought to the Free World by individuals in between 1957 and 1976, and for a short time right after 1991, but this one is a pretty rare bird.
By the way, did it have fences around the strikers, and the Purdey-type button fore-end?
Also, you might want to check out the gun's weight. TOZ had a variation of 20 gauge doubles that weighed around 8 pounds. Those were a fruit of creative thought by a gun guru Ivaschentsev (the same guy that was behind the Buturlin-Matzka Paradox story), and are really a something in terms of wall thickness. Yet they are well-balanced, so the weight doesn't feel.
