In 1866, New Haven Arms Company changed its name to Winchester Repeating Arms Company. First firearm to be built under Winchester name was Model 1866. This first Winchester was a much-improved version of Henry. New magazine tube developed by Nelson King, Winchester's plant superintendent, was a vast improvement over slotted magazine tube used on Henry and its predecessor. Old tube allowed dirt to enter through slots and was weakened because of it. King's patent, assigned to Winchester, featured a solid tube that was much stronger and reliable. His patent also dealt with an improved loading system. Rifle now featured loading port on right side of receiver, with spring-loaded cover. Frame continued to be made from brass. Model 1866 was chambered for .44-caliber Flat Rimfire or .44-caliber Pointed Rimfire. Both cartridges could be used interchangeably.
Barrel on Model 1866 marked with two different markings. First, which is seen on early guns up to serial number 23000 reads, "HENRY'S PATENT-OCT. 16, 1860 KING'S PATENT-MARCH 29, 1866". Second marking reads, "WINCHESTER'S-REPEATING-ARMS. NEW HAVEN, CT. KING'S-IMPROVEMENT-PATENTED MARCH 29, 1866 OCTOBER 16, 1860". There are three basic variations of Model 1866:
1. Sporting Rifle: round or octagon barrel. Approximately 28,000 produced.
2. Carbine: round barrel. Approximately 127,000 produced.
3. Musket: round barrel. Approximately 14,000 produced.
Rifle and musket held 17 cartridges; carbine capacity 13. Unlike Henry, Model 1866s were fitted with walnut forearm. Model 1866 discontinued in 1898, with approximately 170,000 guns produced. Model 1866 sold in various special order configurations such as: barrels longer or shorter than standard, including engraved guns. Prices listed represent only standard-model 1866s. Guns with special-order features, an independent appraisal from an expert is highly recommended. Because of the bright brass frame, they were nicknamed the "Yellow Boy."
Gun Type: | Rimfire Rifle | 1866 First Model RifleFirst style has both Henry and King patent dates stamped on barrel. Flat-loading port cover and two-screw upper tang. Perhaps most distinctive feature of First Model is rapid drop at top rear of receiver near hammer. Often referred to as "Henry Drop", a reference to same receiver drop found on Henry rifle. The First Model is also called the "Flatside." First Models will be seen up through 15000 serial number range.
1866 Second Model RifleSecond style differs from the first most noticeably in its single-screw upper tang and a flare at the front of receiver to meet the forearm. Second Model also has a more gradual drop at rear of the receiver than First Model. Second style Model 1866 appears through serial number 25000.
1866 Second Model Carbine 1866 Third Model RifleThird style's most noticeable characteristic is more moderately curved receiver shape at rear of frame. Serial number now stamped in block numerals behind trigger, thus allowing numbers to be seen for the first time without removing stock. Barrel marking stamped with Winchester address. Third Model found between serial numbers 25000 and 149000. For the first time, musket version was produced in this serial-number range.
1866 Fourth Model RifleFourth style has even less pronounced drop at top rear of frame. Serial number stamped in script on lower tang under lever. Fourth Model seen between serial number 149000 and 170100. Late guns having iron buttplate instead of brass.
1866 Fourth Model Carbine 
