The first Winchester rifle – the Winchester Model 1866 – was originally chambered for the rimfire .44 Henry. Nicknamed the "Yellow Boy" because of its receiver of a bronze/brass alloy called gunmetal, it was famous for its rugged construction and lever-action "repeating rifle" mechanism that allowed the user to fire a number of shots before having to reload. Nelson King's improved patent remedied flaws in the Henry rifle by incorporating a loading gate on the side of the frame and integrating a round, sealed magazine which was partially covered by a forestock.