While the lever-action repeating Henry Rifle of 1860 proved revolutionary in its own right, it still held some limitations within its overall design that the now-Winchester firm soon sought to overcome. The resulting product - the Model 1866 - became an excellent and robust performer along the Western Frontier, offering up reliability and ease of use with accuracy and a 15-round magazine hold. The Winchester Model 1866 was THE Winchester rifle that started it all, beginning the long and successful line of lever-action systems that would become synonymous with the Winchester brand name and the Wild West. Some 720,000 Winchester rifles would eventually be produced during the lever-action market boom, earning the brand a special place in history and in the hearts and minds of its everyday users.
As majority investor, clothing businessman Oliver Winchester purchased the bankrupt assets of the Volcanic Repeating Arms - a firm founded in part by gunsmith's Horace Smith and Daniel Wesson to produce their limited-success Volcanic lever-action pistols and rifles. With complete ownership, Winchester moved the production plant to New Haven, Connecticut, and changed the operating name to the New Haven Arms Company. The firm continued production of the Henry Model 1860 repeating rifle for a time - the rifle named after its shop foreman - Benjamin Tyler Henry. Smith & Wesson eventually left NHAC to begin their own revolver manufacturing company. The Henry Rifle saw some action in the latter years of the American Civil War as well as in the Indian Wars, being produced in approximately 14,000 examples and generally thought of as an excellent rifle for its time. Henry gave the Union soldier lucky enough to acquire it (it was not officially accepted into Union Army use) a hefty 15-round ammunition supply before reloading occurred.
The New Haven Arms Company became the Winchester Repeating Arms Company after the Civil War. One of the first orders was in revising and improving the Henry Rifle. Despite its revolutionary approach to repeating fire, the Henry Rifle was not without limitations. A new rifle was envisioned and became the lever-action repeating Winchester Model 1866, developed as an improved form of the Henry Rifle. The Model 1866 introduced a wooden forestock over the magazine tube as well as a revised sealed magazine chamber and a more robust bronze gunmetal frame. The identifiable Winchester-style loading gate was fitted to the side right side of the frame, easing the process of reloading the weapon. In fact, it was this loading gate that favorably distinguished the Model 1866 over the Henry. The new frame, yellow in appearance, granted the Model 1866 the nickname of "Yellow Boy".
The Model 1866 proved an immediate success for Winchester with some 170,000 examples going on to be manufactured. Furthermore, the weapon appeared in three distinct forms for the mass market - the carbine, rifle and musket. The carbine model was a shortened form, giving up some accuracy for the preferred smaller size, increasing its portability and use from horseback. It was offered with a round 20-inch barrel and became known as the "Saddle Ring Carbine". The carbine made up 127,000 production examples of the entire Model 1866 line, proving it the most popular. The base rifle was known as the "Sporting Rifle", fitting a 24.4-inch round or octagonal barrel as desired. Some 28,000 examples of this type were produced. Perhaps the lesser known of the three became the musket Model 1866 - fitting a rounded barrel and sporting the longer length of the three weapon systems.
Externally, the Model 1866 Sporting Rifle was a very similar design to the Henry Rifle preceding her but became the basic standard design to all those Winchester rifles that followed. The brass receiver made up a small part of the overall design but held the most important inner workings. The loading gate was set to the right side, just above and forward of the lever-action. The lever served as both the trigger guard and the cocking handle, featuring a large, oblong and open-finger loop for a precise hold during movement. The lever-action handle was pulled down and forward, this clearing the chamber of any spent shell casings while introducing a fresh round and cocking the hammer, making the rifle ready to fire. The hammer was typical Winchester, protruding out of the upper rear receiver and within easy reach of the trigger hand. The receiver tapered off into a wooden buttstock with a brass plate and forward-curved end, suitable for setting upon a shoulder during aimed fire. The barrel was octagonal or rounded (depending on the model - carbine, rifle or musket), protruding from the forward portion of the receiver and containing the rear graduated sight and the front post sight along its top facing. The tubular magazine was slung under the barrel, giving the Winchester rifle line their distinct appearance. The new forestock covered nearly have of the magazine tube, externally, and served to protect the operator from a hot barrel - a feature the Henry Rifle lacked.
The Winchester Model 1866 was originally chambered to fire the .44 Henry, the rimfire cartridge developed for the aptly-named Henry Rifle. Rimfire cartridges made use of the firing pin striking the cartridge rim as opposed to its center, as in centerfire cartridges. The cartridge would be produced with its own propellant powder and bullet. Once fired, only the empty "spent" cartridge remained. Later .44 Henry cartridges were made with brass as opposed to the early copper. Fifteen cartridges could be stored in the tubular magazine, each fed backwards via a compression spring with each cocking of the lever.