Revolvers and self-loading pistols are a category of small arms/firearms. They are both handguns that are operated and fired from the hands. They differ by the mechanism through which bullets are fed into the chamber for firing. Modern pistols generally have a detachable magazine containing cartridges; their chamber forms an integral part of the barrel, or is at least permanently aligned with it. Revolvers on the other hand feature a revolving cylinder which rotates with every shot to bring the next cartridge in line with the barrel.
Historically, the term ‘pistol’ was synonymous with ‘handgun’. In modern use, however, ‘pistol’ is often used to refer to gas-operated self-loading handguns with a detachable magazine containing numerous cartridges. Three variants of pistols can be identified: single-shot, derringer (small pocket firearms with multiple barrels, each loaded and fired separately), and self-loading. Revolvers, by contrast, feature a revolving cylinder that houses several (usually five to seven) separate chambers, each of which contains a cartridge. Again, three variants can be identified: the ‘swing out’ form, whereby the cylinder is pushed to the left to expose the chambers; the ‘break top’, where the barrel and cylinder swing down from the base of the weapon to expose the back of the cylinder; and the solid frame revolver, the oldest system, where the back of the cylinder is partially exposed and each chamber is loaded individually by rotating it manually.
Military small arms inventories will typically include 13% pistols (compared to 72% assault rifles, 6% machine guns, and 9% other small arms).
Pistols and revolvers are covered by a range of multilateral instruments (treaty and soft law) regulating small arms. Machine pistols are treated in the Encyclopedia entry on sub-machine guns.