Cimarron 1866, Yellowboy Sporting, Lever Action Rifle, 45 Long Colt, 24 Octagon Barrel, Brass Receiver, Blued Barrel, Walnut Stock, 10 Rounds CA229 Originally known as the Improved Henry due to its patented loading gate on the side of the frame, designed by Nelson King, Winchester's plant superintendent, and the addition of a wood forearm, the 1866 model was known as the Yellow Boy by the Native Americans, because of its brass frame.