Bolt-action is a type of manual firearm action that is operated by directly manipulating the bolt via a bolt handle, most commonly placed on the right-hand side of the firearm. The majority of bolt-action firearms are rifles, but there are also some variants of shotguns and handguns that are bolt-action. A firearm using bolt-action mechanism is colloquially referred to as a bolt gun.
The AWM sniper rifle, a bolt-action rifle
A US Marine extracts a fired cartridge from an M40A3 using a bolt-action mechanism
A disassembled Karabiner 98k action
Close-up of the action on an SMLE Mk III rifle, showing the bolt head, magazine cut off, and charger clip guide.
In firearms terminology, an action is the functional mechanism of a breech-loading firearm that handles the ammunition cartridges, or the method by which that mechanism works. Actions are technically not present on muzzleloaders, as all those are single-shot firearms with a closed off breech with the powder and projectile manually loaded from the muzzle. Instead, the muzzleloader ignition mechanism is referred to as the lock.
A view of the break-action of a typical double-barreled shotgun, with the action open and the extractor visible. The opening lever and the safety catch are clearly visible.
Smith and Wesson M&P revolver
Barreled action for bolt-action rifle
U.S. M1895 Lee Navy straight-pull rifle