This appears to be a stylistic combination of a Northampton/Neihart domed lid teamed up with an Angstat finial. How old is it? Can't say, but probably first quarter of the 1800s. The finial is that of one of the Angstats, perhaps Peter, or Jacob, who no doubt made the rifle that this box came with. Too bad the rest of the old rifle is now gone.
The profile of the stock on the new rifle seems to emulate that of Peter Angstat. Very appropriate! Is there some story or history that goes with this piece? Thank you for posting it. Always fun to see good things.
Dick