My Uncle just purchased this shotgun at a gun show. It has no markings at all that we can find except 1854 or 1864 stamped between the barrels underneath the ramrod.
Many blacksmiths and hobbyists made guns years back,especially shotguns.Some didn't stamp/mark them.Have you taken the wood off and looked under it?There may be something.The design is a European fowling piece. ,,,sam.