A revolver (also called a wheel gun) is a repeating handgun that has a revolving cylinder containing multiple chambers and at least one barrel for firing. Revolvers are a subset of handguns, distinct from pistols, which are defined as handguns with an integral chamber-barrel assembly. The revolver allows the user to fire multiple rounds without reloading after every shot, unlike older single shot firearms. After a round is fired the hammer is cocked and the next chamber in the cylinder is aligned with the barrel by the shooter either manually pulling the hammer back (single action operation) or by rearward movement of the trigger (double action operation).
Revolvers still remain popular as back-up and off-duty handguns among American law enforcement officers and security guards and are still common in the American private sector as defensive and sporting/hunting firearms. Famous and iconic revolvers models include the Colt 1851 Navy Revolver, the Webley, the Colt Single Action Army, the Colt Official Police, Smith & Wesson Model 10, the Smith and Wesson Model 29 of Dirty Harry fame, and the Nagant M1895.
Though revolvers are usually referred to as and often are handguns, other firearms may also have a revolver action. These include some models of grenade launchers, shotguns, rifles and cannons. These are different from other firearms with revolving chambers, such as Gatling-style rotary cannons in that revolvers typically require the hammer to be re-cocked with each shot and require manual reloading, while guns like the minigun are motor driven and have a barrel for each chamber.