Springfield Model 1866

The Springfield Model 1866 was the second iteration of the Erskine S. Allin designed trapdoor breech-loading mechanism. Originally developed as a means of converting rifled muskets to breechloaders, the Allin modification ultimately became the basis for the definitive Springfield Model 1873, the first breech-loading rifle adopted by the United States War Department for manufacture and widespread issue to U.S. troops. The Model 1866 corrected problems encountered with the prototypical Springfield Model 1865, in particular a simplified and improved extractor and a superior .50 caliber centerfire cartridge (the Model 1865 used a .58 caliber rimfire cartridge with mediocre ballistics), among many other less significant changes. It employed a robust version of the trapdoor breechblock design originated by Erskine S. Allin, Master Armorer of the Springfield Armory. Approximately 52,000 .58 caliber Springfield Model 1863 rifled muskets were converted by Springfield Armory for use by U.S. troops, the barrels being relined and rifled to .50 caliber and the trapdoor breech system affixed. About half of the rifles produced were shipped to Europe for use in the Franco-Prussian War. The rifle was chambered for the powerful centerfire .50-70-450 cartridge (.50 caliber 450-grain (29 g) bullet; 70 grains (4.5 g) of powder). Though a significant improvement over the extractor of the Model 1865 rifle, the Model 1866 extractor was still excessively complicated and the extractor spring somewhat prone to breakage. However, it is a misconception that a broken extractor disabled the weapon. In the official 1867 government user booklet “Description and Rules for the Management of the Springfield Breech-Loading Rifle Musket, Model 1866”, the following is stated regarding a broken extractor and/or ejector: “It should be understood that the ejector and friction springs are convenient rather than necessary, and that the piece is not necessarily disabled if one or both of them should break, for...