Single shot

Single-shot firearms are firearms that hold only a single round of ammunition, and must be reloaded after each shot. The history of firearms began with single-shot designs, and many centuries passed before multi-shot designs became commonplace. Single-shot designs are less complex than revolvers or magazine-fed firearms, and many single-shot designs are still produced by many manufacturers, in both cartridge- and non-cartridge varieties, from zip guns to the highest-quality shooting-match weapons.

The vast majority of firearms before the introduction of metallic cartridges in the 1860s were single-shot and muzzle loading. However, multi-barrel, breech loading, revolving, and other multi-shot firearms had been experimented with for centuries. Notable pre-cartridge era single-shot firearms included matchlock, wheellocks, snaplock, doglock, miquelet locks, flintlock, and percussion cap firearms. Muzzle loaders included Brown Bess muskets, Charleville muskets, Kentucky Rifles, dueling pistols, M1841 Mississippi Rifle, Springfield Model 1861 and many others. There were also breech loading pre-cartridge era single shots such as Hall rifles, Fergussion rifles, Sharps rifles, and several others.

Almost all of the early cartridge-fed rifles were single-shot designs, taking advantage of the strength and simplicity of single-shot actions. A good example is the "trapdoor" or Allin action used in early cartridge conversions of 1863 Springfield muzzleloading rifles. The conversion consisted of filing out (or later milling out) the rear of the barrel, and attaching a folding bolt, the "trapdoor", that flipped up and forwards to allow the cartridge to be loaded in the breech. Once loaded, the bolt was closed and latched in place, holding the round securely in place. The bolt contained a firing pin that used the existing percussion hammer, so no changes were required to the lock. After firing, the act of opening the bolt would partially extract the fired case from the chamber, allowing it to be removed. In 1866, the United States standardized on the .50-70 cartridge, chambered in trapdoor conversions of rifled muskets that had been used in the American Civil War. The trapdoor mechanism continued with the adoption of the Springfield 1873 rifle, chambered in the new .45-70 cartridge. The Springfield stayed in service until 1893, when it was replaced by the Krag–Jørgensen bolt-action rifle.

...
Wikipedia