In firearm designs, the term single-shot refers to guns that can hold only a single round of ammunition inside and thus must be reloaded manually after every shot. Compared to multi-shot repeating firearms ("repeaters"), single-shot designs have no moving parts other than the trigger, hammer/firing pin or frizzen, and therefore do not need a sizable receiver behind the barrel to accommodate a moving action, making them far less complex and more robust than revolvers or magazine/belt-fed firearms, but also with much slower rates of fire. The history of firearms began with muzzleloading single-shot firearms such as the hand cannon and arquebus, then multi-barreled designs such as the derringer appeared, and eventually many centuries passed before breechloading repeating firearms became commonplace. Although largely disappeared from military usage due to insufficient firepower, single-shot firearms are still produced by many manufacturers in both muzzleloading and cartridge-firing varieties, from zip guns and ultra-concealable pocket pistols to the highest-quality hunting and match rifles. History Pre-cartridge era The vast majority of firearms before the introduction of metallic cartridges from the 1860s onwards, were single-shot muzzleloaders. However, multi-barrel, breechloading, revolving, and other multi-shot firearms had been experimented with for centuries. Notable pre-cartridge era single-shot firearms included matchlock, wheellock, snaplock, doglock, miquelet lock, flintlock, and percussion cap firearms. Muzzleloaders included the Brown Bess, Charleville and Springfield Model 1861 muskets, the Kentucky and Mississippi rifles, and the duelling pistol. There were also early breech-loading single-shot rifles such as the Hall, Ferguson, and Sharps. Cartridge era Rifles 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 Springfield Model 1866 rifle and .50-70 cartridge, chambered in trapdoor conversions