Revolver

A revolver works by having several firing chambers arranged in a circle in a cylindrical block that are brought into alignment with the firing mechanism and barrel one at a time. A single action revolver requires the hammer to be pulled back by hand before each shot. In contrast, in a double action revolver, squeezing the trigger can pull back the hammer to cock the gun as well as serving to release the hammer. Most modern double action revolvers can also be fired in single action mode, which serves to improve the accuracy by reducing the force and distance required to pull the trigger. A few designs, however, have fully-concealed hammers and are double-action-only. Because the effort required to cock the hammer is part of the firing action in double action revolvers, they can generally be fired faster than a single action, but at the cost of reduced accuracy in the hands of most shooters.

Most commonly, such guns have a 5 or 6 shot capacity (hence the more common names of 'six-gun' or 'six-shooter'); however, some revolvers have a 7, 8, 9, or 10 shot capacity (this often depends on the caliber, though different companies produce revolvers in the same calibers with different capacities, due to other design differences), and each chamber has to be reloaded manually. This makes the procedure of reloading such a weapon slow. The alternatives are a replaceable cylinder, a speedloader (manufactured by HKS and Safariland) which can reload all chambers at once, or a moon clip that holds a full load (or even half of one in the case of a half-moon clip) of ammunition and that is inserted along with the ammunition. Bianchi manufactures a product known as a "speedstrip". Speedstrips cannot reload a completely empty revolver as rapidly as a speedloader, but are less expensive, flatter, and more flexible when it comes to partial reloads.

Compared to autoloading handguns, a revolver is often simpler to operate (despite often being more mechanically complex) and may have greater reliability (depending on factors such as firmness of grip, ammunition or cartridge used, and degree of maintenance and lubrication provided to the firearm). For example, should a semiautomatic pistol fail to fire, clearing the chamber requires manually cycling the action to remove the errant round, as cycling the action normally depends on the energy of a cartridge firing. With a revolver, this is not necessary as none of the energy for cycling the revolver comes from the firing of the cartridge, but is supplied by the user either through cocking the hammer or, in a double action design, by just squeezing the trigger.

Over the long period of development of the revolver, many calibers have been used. Some of these have proved more durable during periods of standardization and some have entered general public awareness. Among these are the .22 rimfire, a popular target shooting caliber; .38 Special and .357 Magnum, known for its police use; the .44 Magnum, famous from Clint Eastwood's "Dirty Harry" films; and the .45 Long Colt, used in the Colt revolver of the "Wild West". Introduced in 2003, the Smith & Wesson Model 500 is the most powerful production revolver ever created, using the .500 S&W Magnum round.

era with 9 revolving chambers firing bullets and a center barrel firing The LeMat Revolver, an unusual revolver from the American Civil Warshot.

As revolvers are of a 19th-century design, it is not surprising that semi-automatic pistols have largely overtaken them in military and law enforcement applications. Their lower ammunition capacities and relatively longer reload times compared to autoloading pistols are the main reasons for the switchover that occurred in the 1980s and 1990s. Additionally, the flat profile of semi-automatics make them more suitable for concealed carry. Revolvers still remain popular in the role of back-up (and off-duty) guns among American law enforcement officers and security guards. Also, revolvers are still common in the American private sector as defensive and sporting/hunting firearms.

Famous police and military revolvers include the Webley, the Colt Single Action Army, the Smith & Wesson Model 29, the Smith & Wesson Model 10, and the Smith & Wesson 1917.

Revolver technology does live on in other weapons used by the military. Some autocannons and grenade launchers use mechanisms similar to revolvers, and some riot shotguns use spring loaded cylinders holding up to 12 rounds.

In addition to serving as backup guns, revolvers still fill the specialized niche role as a shield gun; law enforcement personnel operating a ballistic shield sometimes opt for a revolver instead of a self-loading pistol as a Gun shield, as the latter's slide may strike the front of the shield when fired; revolvers do not suffer from this disadvantage. A second revolver may be secured behind the shield to provide a quick means of continuity of fire.