In the wake of the Civil War, the US Army recognized that many of its small arms were obsolete, and needed replacement. For handguns, the main user was the cavalry, for whom a handgun was still seen as a secondary weapon to a saber. While modern metallic cartridges were fairly well established by the time of the main Army handgun trial in 1869, the Rollin White patent on bored-through cylinders was still in force, and the only real option for breechloading revolvers were S&W’s .22 rimfire models. The Army tested these against the Remington rolling block single-shot pistol in .50CF (aka .50-25; 300 grain bullet over 25 grains black powder with a 600 fps muzzle velocity), found the rolling block to be the better option, and ordered 5,000 of them as the Model 1871.
The Army didn’t actually pay for the new pistols; they traded 5,000 unissued Remington New Model army revolvers that were still in storage for them. It does seem odd for the Army to be trading 6-shooters for single-shot pistols, but there you have it. The deal was great for Remington, as the market value of the revolvers was higher than the production cost of the rolling blocks, and they made a nice profit reselling the revolvers (which they had already been paid for once before) after retrofitting them for metallic cartridges after the Rollin White patent expires. The Army began issuing the pistols in 1872, but only about a quarter of them got into the field before the Army adopted the new Colt 1873 revolver and began using that instead.
