I think it is very possible. Hercules Dousman was a partner in the American Fur Company that lasted until 1842. He lived in Prairie du Chien, Wisconsin. His home is now a state park, Villa Louis. My 3rd great grandfather worked for Dousman, first as a voyageur and then as a courier. I live in SW Wisconsin about an hour east of Prairie du Chien. I imagine many trade guns made their way through the warehouses there. In fact, I bought a relic NW trade gun at a farm auction about half way between there and where I live now. While I have no proof, I like to think it came from there, and that perhaps my old grand dad had something to do with it. Somewhat further north of there in Black River Falls, Wisconsin, I bought another relic home-made barn gun sort of thing. It had an old trade gun style barrel with Belgium proofs. So I think what you're proposing is quite reasonable.