I would heed David's advice and at least check the chamber as he suggests. If you don't know who David of D&T is, try searching for D&T Custom Rifles. I dare say he has more experience with single shot rifles (building them and shooting them) than half of the members of this forum put together.
Oh believe me, I follow all of his threads. I've actually got a 7.92x57 barrel I've been thinking about stubbing.