During the post Civil War period the U.S. Government experimented heavily with developing metallic cartridge rifles. One of the most cost effective methods for the Government was by taking left over muzzle loaders and converting them into single shot metallic breech loaders. The primary conversion method was using the Allin conversion on 1863 rifles during the 1868 to 1870 time period. Several variations were developed, all with very low production numbers, using the 50-70 centerfire cartridge. This series of rifles and carbines eventually evolved into the successful Model 1873 Rifle and Carbines Series. In 1870 the last variations of rifle and carbines were manufactured, this carbine being one of them. Only 341 total of these carbines were manufactured, and the fact that the U.S. Government was entering the Indian War period it is amazing that any survived at all. The characteristics of this model are there is no serial number, and the 2 3/16" high arch breech block is marked "1870/eagle head/crossed arrows/US". The lock plate is dated "1863" at the rear and the eagle shield motif and "U.S./SPRINGFIELD" ahead of the hammer. It has the correct two-click tumbler, two piece trigger guard, saddle ring and bar mounted on the left side of the stock and folding ladder rear sight. The buttplate is "U.S." marked without the compartment.