The first production of a carbine model of the Trapdoor Springfield was the Model 1870 (excluding 4 prototypes produced in 1868). There was a focus infantry rifles in theTrapdoor program, and just 362 of these carbines were made in 1870. They use the short receiver of the 1870 rifle, a 21 3/4” barrel, a slinger and ring on these in place of sling swivels, and are not serialized. They also use a unique narrow rear sight slider, for no apparent reason.
The 1870 pattern was the last of the .50-70 Trapdoors, to be supplanted in 1873 by the new .45-70 cartridge. The two main improvements of the type were the shorter receiver (the use of sleeved barrels previously made a longer receiver necessary) and an increase in the opening arc of the breech block (to make it less likely to fall shut inadvertently).