First mass-produced true breech-loading cartridge firearm. Manufactured in a national armory. Actions were supplied by Joslyn Firearms Company. Chambered for .56-50 rimfire cartridge. Has 35.5" round barrel and full-length stock that is held on by three barrel bands. Lock marked "U.S./Springfield" with "1864" at back. Barrel marked "B. F. Joslyn's Patent/ Oct. 8th, 1861 / June 24th, 1862". Approximately 3,000 manufactured circa 1865. Probably issued to Union forces, but unknown if they saw action before end of Civil War.