I have thought about this since chiming in earlier. That piece was made by a very competent gunsmith. It was made for a sporting gentleman--thus the rifle barrel and fowling barrel on one shoulder stock. The stock looks like fairly normal walnut (if it's maple, the varnish or oil finish is so darkened as to hide the maple). That said, I believe a gunsmith capable of making such a piece for a client who desired such a piece would have signed it somewhere. Heed kevikens advice about insuring it and keep all your photos of it on a disk in your safety deposit box with other valuables. Don't try to take any parts off of it yourself. You can find numerous double barrel percussion rifles by google searching those particular words, but I have yet to find a rifle / shotgun combination of this vintage.