One of the many things that have gone through my brain in the many sleepless nights recently was the fact that MANY of the early breech loaders did not function well and so they permanently closed the breech and served them from the muzzle. if this piece is otherwise acceptable maybe you could build an ml and add the parts to make it Look like a "locked up" breech loader . it seems like an 1850-51 breech loader would be suspect! sounds like a lot of work, but it would be different!
Dave