I'll add my second to what E.vonAschwege said in previous post. Too bad someone took off much/all original finish, and that act has diminished the value of this piece to a collector.
Sadly, that act is irreversible. Any attempt to restore the original finish, as it would look today after 150 or so years, without disclosing this to the purchaser, makes it a fake ... and somehow someone will figure this out. If you want to sell it, describe it honestly, and price it accordingly, as there are collectors who will still buy it.
A nice example nonetheless, so wax the wood, brass fittings, and barrel and know that it is stable and in good hands.