Despite the nomenclature, 56-50 rimfire cartridge actually fires a 0.55″ diameter bullet. It was pretty potent for a rimfire, on the order of 350gr and 1200fps, about on par with 44 Magnum from a long-barreled revolver. Tubular magazine in the stock holds 7 rounds, the lever only loads cartridges and extracts casings — the hammer must be cocked separately for each shot. The sights are marked — most optimistically, for 800 yards, at which point velocity was down to 600fps and the bullet drops more than 40 yards. In the photo, her sights are set to 300. For 1860, Spencer rifle was quite an impressive device. Modern centerfire reproductions are available.