Designed to replace the model 1863 musket, early trapdoors were made by converting muskets to breech loaders. The trapdoor fires the now famous 45-70 cartridge. Operated by cocking the hammer and raising the breechblock forward. The model 1873 trapdoor saw many variations and improvements during its service life until it was replaced by the Krag Jorgensen in 1892. Breech block is marked "U.S./MODEL/1873". Lock is marked "U.S./Springfield". Cartouche on the left side of the stock is dated "1884". A "Circle P" cartouche is present on the wrist of the stock but the "P" is script.