Referred to as the “Improved Henry”, the Model 1866 lever-action repeater was the first model to be called a Winchester. Its distinctive brass colored frame (technically an early form of bronze, also called “gunmetal”) gave rise to the nickname “Yellow Boy”.
The most important notable improvement over the Henry was the addition of the Nelson King’s patented cartridge loading gate system which allowed for a closed magazine tube and a wood forend. The Model 1866 fired the same .44 caliber rimfire round as the Henry rifle; however; cartridge improvements made a shorter carbine barrel length practical. The ’66 was offered in rifle, carbine, or musket configurations with standard barrel length for the rifles 24”; carbines, 20”; and muskets, 27”.
During its production run from 1866 to 1898, nearly 160,000 were made. Serial numbers began in the mid-12,000 range (overlapping with Henry’s serial numbers which ended around 14,900) and carried just into the 170,000 range. First Models have flat-side receivers. Second, Third and Fourth Models have a flared receiver to accommodate a thicker forend.
Original Winchester factory records are available for this model from the Cody Firearms Museum in Cody, Wyoming, from serial number 124995 thru 170101. Also available: 35,527, 35,952, 36,200, 96,740, 96,743, 96,745, 103,672, 104,463, 104,469, 104,470, 107,208, 107,209, 109,650, 109,651, 112,269, 112,270, 112,274, 119,180, 119,488, 119,567, 119,579, 119,739, 120,072, 120,593, 120,665, 121,191, 121,964, 124,005, 124,357, 124,876, 124,893, 124,899.