Bolt (firearms) in the context of "AK-74"

The chamber of a firearm is the cavity at the back end of a breechloading weapon's barrel or cylinder, where the ammunition is inserted before being fired. The rear opening of the chamber is the breech, and is sealed by the breechblock or the bolt.

Bolt action is a type of manual firearm action that is operated by directly manipulating the turn-bolt via a bolt handle, most commonly placed on the right-hand side of the firearm (as most users are right-handed). The majority of bolt-action firearms are rifles, but there are also some variants of shotguns and handguns that are bolt-action.

Bolt action firearms are generally repeating firearms, but many single-shot designs are available as well, particularly in shooting sports where single-shot firearms are mandated, such as most Olympic and ISSF rifle disciplines.

A semi-automatic firearm, also called a self-loading or autoloading firearm (fully automatic and selective fire firearms are also variations on self-loading firearms), is a repeating firearm whose action mechanism automatically loads a following round of cartridge into the chamber and prepares it for subsequent firing, but requires the shooter to manually actuate the trigger in order to discharge each shot. Typically, this involves the weapon's action utilizing the excess energy released during the preceding shot (in the form of recoil or high-pressure gas expanding within the bore) to unlock and move the bolt, extracting and ejecting the spent cartridge case from the chamber, re-cocking the firing mechanism, and loading a new cartridge into the firing chamber, all without input from the user. To fire again, however, the user must actively release the trigger, and allow it to "reset", before pulling the trigger again to fire off the next round. As a result, each trigger pull only discharges a single round from a semi-automatic weapon, as opposed to a fully automatic weapon, which will shoot continuously as long as the ammunition is replete and the trigger is kept depressed.

Ferdinand Ritter von Mannlicher produced the first successful design for a semi-automatic rifle in 1885, and by the early 20th century, many manufacturers had introduced semi-automatic shotguns, rifles and pistols.