I had a similiar smoothbored musket/rifle relined to .50, for $200, and it's a great shooter.
Have you removed the barrel to check the underside? Do you plan to clean the wood or the barrel? I cleaned the wood on a Springfield trapdoor 50-70 last summer and found the faint cartouche.
I would not take the lockwork apart unless you know how to do it (but I would remove it from the stock). Check the back side of the lockwork for inspector's marks.
Can you post some pics?
Last edited by pohill; June 18, 2012 at 08:51 PM.