Those elaborately carved stocks were popular in Germany but not in England or the U.S. (or, for that matter, in Belgium). I suspect the gun was made for export to Germany, then somehow made its way to the U.S.
I doubt you will ever be able to determine the maker, or even the date manufactured. Those guns were made by the ton in Liege by "consortiums" or "guilds", groups of gun makers, each of whom specialized in one part (locks, barrels, stocks, etc.). The parts were then assembled by yet another shop. To have put all the maker's names on the guns would have required a billboard, so the guns were not marked with any name at all.
Jim