Was it pre-1898? If so, Cabelas would be technically correct. No C&R or FFL needed.
Otherwise Lefevers are pretty easy. They are listed by name in the C&R book. All Lefevers (including Nitros) are eligible. Its when you get to the small obscure manufacturer that is not listed in the C&R book that it gets interesting.


Great-Great Grandson of D.M. Lefever
www.lefevercollectors.com