Aaron: #150880 would be a F grade Hammer Gun made in 1907. #50880 could be a Bar Action Lock Hammer Gun made in 1895 or a Back Action Lock made in 1922. I'd suggest you post detailed pics of the flat part of the receiver, the flat part of the barrels, and the top of the barrels. The barrels on 1902-1932 F grades should have 'Hunter Arms Co. Fulton, N.Y.' stamped on the RIB.