I recently purchased an 1873 Springfield Trapdoor that was actually made in 1874, serial 14xxx. Examining it closely, it looks like there is a large pit or chip in the chamber that seems to be right next to or right at the joint where receiver and barrel seem to join. A dental pick sinks in pretty far but there is no other problems apparent with the rifle. Is there a means to close up and smooth out the pit to allow it to fire or is this a lost cause? The barrel and receiver scrib marks line up OK. I have no means to separate them to examine the threads and connection more closely.