Springfield Model 1868

The Springfield Model 1868 was one of several model "trapdoor Springfields", which used the trapdoor breechblock design developed by Erskine S. Allin. Originally, the trapdoor Springfields were created to convert Model 1863 Springfield rifled muskets to breech loading rifles at a relatively low cost. This conversion consisted of replacing the percussion lock with the breech loading trapdoor mechanism, and relining the barrels to convert them from .58 to .50 caliber. This proved problematic, because in the field, the lining tended to separate from the barrel.

To correct this problem, the Model 1868 used a new barrel instead of relining the original older barrel. The new barrel was slightly shorter, 32.5 inches, compared to the 36.5 inch barrel used on the Model 1866. The shorter barrel was affixed using only two barrel bands, instead of the three used on the Model 1866. Since it lacked the middle barrel band, the sling was affixed to the upper barrel band instead. The Model 1868 also differed from previous models in that it used a separate Allin type receiver with the barrel attached to it. The Model 1868 was also the first trapdoor conversion to use the cartridge extractor covered by U.S. Patent No. 68,009, issued August 27, 1867 to W.H. & G.W. Miller. The Model 1868 had an overall length of 51$7/8$ inches.

Over 50,000 Model 1868 rifles were manufactured, chambered for the .50-70 450 cartridge. This model served as the basis for the definitive Model 1873 "Trapdoor Springfield" series of rifles in .45-70-405 caliber, which was adopted in 1873 as the standard military longarm of the United States armed forces for the next 20 years.

In the late 1860s and early 1870s, many army units continued to use outdated rifled muskets and other weapons like the Spencer and Sharps .52 caliber percussion rifle. The army wanted to standardize weapons and ammunition, and forced these units to switch to trapdoor Springfields once the Model 1868 went into full production.

A Model 1868 Carbine version was experimented with, but never went beyond the prototyping stage. The Carbine version had a 22$1/4$ inch barrel.