In firearms, an extractor is a part in a breechloading weapon that serves to remove casings of previously fired cartridges from the chamber, so new rounds of ammunition can be loaded for firing. In repeating firearms with moving bolts, the extractor is often aided by an ejector, which expels the casings entirely out of the gun.
Extractors can be found on bolt-action, lever-action, pump-action, semi-automatic and fully automatic firearms. Break-action shotguns and double rifles, such as those with single or double barrels, typically have an extractor that operates when the action is broken open. Extractors are also found on revolvers, removing cases either in succession (as in a fixed-cylinder single-action revolver) or simultaneously (as in a double-action revolver with a swing-out or top-break cylinder). ...