Modern Gatling-style guns

After Gatling guns were replaced by lighter, cheaper blowback-style weapons, the approach of using multiple rotating barrels fell into disuse for many decades. However, Gatling gun-style weapons made a return in the 1940–50s, when weapons with very high rates of fire were needed in military aircraft. For these modern weapons, electric motors are used to rotate the barrel, although systems that derive power from their ammunition do exist such as the GSh-6-23, which uses a gas-operated drive system.

One of the main reasons for the resurgence of the Gatling gun-style design is the weapon's tolerance for continuous high rates of fire. For example, if 500 rounds were fired at a high rate from a conventional single-barrel weapon, this would likely result in the barrel overheating (distorting in extreme cases) or a weapon jam. In contrast, a five-barreled Gatling gun-style weapon firing 500 rounds, only fires 100 rounds per barrel, an acceptable rate of fire. Ultimately the limiting factor is the rate at which loading and extraction can occur. In a single barrel design these tasks must alternate, a multiple barrel design on the other hand lets them occur simultaneously, with different barrels at different points in the cycle. Their high rate of fire also makes them useful in systems that have little time to engage their targets, such as CIWS which defend against fast-moving anti-ship missiles.

The M61 Vulcan 20 mm cannon is the most prolific member of a family of weapons designed by General Electric and currently manufactured by General Dynamics. It is a six-barreled rotary cannon capable of more than 6,000 rounds per minute. Similar systems are available ranging from 5.56 mm to 30 mm (there was even a 37 mm Gatling on the prototype T249 Vigilante AA platform); the rate-of-fire being somewhat inversely-proportional to the size and mass of the ammunition (which also determines the size and mass of the barrels).

Another Gatling design well-known among aviation enthusiasts is the GAU-8 Avenger 30 mm cannon, carried on the A-10 Thunderbolt II (Warthog) attack aircraft. It is a seven-barreled cannon designed for tank-killing and is currently the largest bore Gatling weapon active in the U.S. arsenal.

During the Vietnam War, the 7.62 mm caliber M134 Minigun was created as a helicopter weapon. Able to fire 6,000 rounds per minute from a 4,000-round linked belt, the Minigun proved to be one of the most effective non-explosive projectile weapons ever built and is still used in helicopters today.

They are also used on USAF AC-47, AC-119 and Lockheed AC-130 gunships, their original high-capacity cargo airframes able to house the items needed for sustained operation. With sophisticated navigation and target identification tools, Miniguns can be used effectively even against concealed targets. The crew's ability to concentrate the Gatling's fire very tightly produces the appearance of the 'Red Tornado' from the light of the tracers, as the gun platform circles a target at night.

The GAU-8 Gatling gun of an A-10 Thunderbolt II at Osan Air Base, Korea.

The Minigun features in several action movies including Terminator 2 and Predator, but in reality they are unusable as unmounted personal weapons, the high rate of fire (with accompanying recoil), mechanical and power-supply complexity and heavy weight making them impractical compared to a light machine gun.

Gatling Gun

A Gatling gun is a gun with multiple firing pins and breeches connected to multiple rotating barrels. Each barrel fires a single shot as it reaches a certain point in the cycle after which it ejects the spent cartridge, loads a new round, and in the process, somewhat cools down. This configuration allows higher rates of fire without the problem of an overheating single barrel, though accuracy suffers. The gun was designed by the American inventor Dr. Richard J. Gatling in 1861 and patented in 1862.

Although it was not an automatic firearm, the Gatling gun is considered by some to have been the first machine gun. While the Gatling gun did not automatically reload under its own power, it was capable of firing continuously. The first Gatling gun relied on a hand crank for external power. The Maxim gun, invented in 1884, was the first self-powered machine gun. Some time later, Gatling-type weapons were invented that diverted a fraction of gas from the chamber to spin the rotating barrels. Later still, electric motors supplied external power.

Mitrailleuse

The mitrailleuse was a manually-fired volley gun originally developed in Belgium in the 1850s by Fafschamps and improved during the early 1860s by Christophe and Montigny. The French-designed Reffye mitrailleuse followed soon afterwards and was adopted by the French Army in 1865, with the personal support of Napoleon III. Initially kept under wraps as a secret weapon, it became widely used in battle by French artillery during the Franco-Prussian War (1870-1871). Smaller numbers of other designs, including the Gatling gun, were also purchased by the French government during the latter part of that conflict. The Reffye mitrailleuse had initially been built in small numbers and in secrecy: only about 200 were available for field deployment in July 1870 at the beginning of the conflict. Historically, however, it was the first rapid-firing weapon to be deployed as standard equipment by any army in a major conflict. Although innovative, it failed as a tactical weapon because its operational usage and design were flawed. The word mitrailleuse nonetheless became the generic term for a machine gun in the French language, although the mitrailleuse itself was entirely manually-operated.

Machine gun

A machine gun is a fully-automatic mounted or portable firearm, usually designed to fire rifle cartridges in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute. The first machine guns were manually operated, for example, by turning a hand crank.

In United States law, machine gun is a term of art for any fully-automatic firearm, and also for any component or part that will modify an existing firearm into a fully-automatic firearm.

Operating principles

There have been two main machine gun eras: the era of manual machine guns and the era of mason machine guns. The technical development itself is marked by a series of developments of specific automatic features, as well as technical developments (such as linked ammunition). The era of manual multi-shot devices extends back hundreds of years (such as manual volley guns), but the development of manual and automatic machine guns takes place almost entirely in the latter half of the 1800s. Manual machine guns are manually-powered, e.g., a crank must be turned to power reloading and firing, as opposed to simply holding down a trigger, as with automatic machine guns. There are many other notable features, but this is one of the most significant to allowing higher rates of fire common to machine guns.

Manual machine guns, as well as manual volley guns, saw their first major use in the American Civil War. The Gatling gun and "coffee gun" both used manually-powered automatic loading, fed via a hopper filled with cartridges. The Gatling gun would be the major type of the late 19th century, though there were many other manual designs with varying degrees of use (e.g. the Nordenfelt gun). The first automatic machine gun was the recoil-operated Maxim gun, which used linked (belt) ammunition, as well as a single barrel and automatic loading. This concept of using bullet energy would also drive the development of nearly all other semi and fully automatic firearms of 20th century.

The two major operation systems of modern automatic machine guns are gas operation and recoil operation. As the name implies, the gas operated system uses the gas generated from the burning powder to cycle the action, whereas the recoil operated uses the recoil generated from the ejecting bullet. The first gas-operated machine gun was the Colt-Browning M1895.. It was followed shortly thereafter, in 1897, by the gas-operated Hotchkiss machine gun.

Another (minor) type is the externally-powered machine gun. Rather than human manual power or energy generated by the cartridge, an external source such as an electric motor is used. These types are now called by more specific names such as Minigun and Chain gun. They are common on fighting aircraft and ground vehicles, where the externally powered mechanism allows for automatic clearing of many failure conditions that would otherwise disable the firearm.

General purpose machine gun

A general purpose machine gun (GPMG) in concept is a multi-purpose weapon, a machine gun intended to fill the role of either a light machine gun or medium machine gun, while at the same time being man-portable. However, performance in either role may be inferior to a weapon specifically designed for that role. In modern practice, they are air-cooled medium machine guns firing rifle cartridges such as the 7.62x51mm NATO. They are generally operated from a stationary prone position from either a bipod or tripod, or mounted on a vehicle, as they are usually too powerful and heavy to be fired effectively on foot from an unsupported standing position or on the move.

The term GPMG (or "Jimpy" in British Army slang), which comes from the Belgian-French name Mitrailleuse d'Appui General or General Purpose Machineguns (GPMG), became popular for describing medium machine guns used in multiple roles. The original Belgian-French term Mitrailleuse a Gaz is also known to be used. The mediums fired rifle caliber ammunition, but had some concessions for more extended firing and more general usage. This generally included both bipod and tripod/pintle mounting options and quick-change barrels. The first medium machine gun used as a GPMG traces back to World War I, where aircooled medium machine guns were used in many different roles, typically with larger magazines on aircraft, tanks, and ships, and in lighter configurations by infantry on bipods or tripods.

During the inter-war period, Germany developed the Maschinengewehr 34, or MG34, from scratch as a GPMG, as opposed to an adaptation of an existing weapon, such as the MG08/15. The MG34 was air-cooled, belt-fed and had the ability to be mounted on a variety of fixtures and employed in several different roles. Notably, the MG34 remained the standard co-axial weapon for Nazi German vehicles through the Second World War. The MG34 was successful enough during use in the opening stages of the Second World War that the concept of the GPMG was adopted in many other post-WWII armies. The MG 34's immediate successor in Wehrmacht service, the MG42, was the most versatile and effective machine gun design of the Second World War. The MG3, a direct descendant of the MG42, is still in service with the German Army and others.

Belgian-made FN MAG.

The Belgian FN MAG, FN Mitrailleuse d'Appui General (general purpose machine gun) has long been the most widely-used GPMG among NATO and other western armies. The British Army and other Commonwealth forces used it to replace the venerable Vickers Gun, beginning in the late 1950s. It is known as the "Gympy"(Sometimes spelt "Jimpy") in British Army slang.

M240G general purpose machine gun.

The US Army has adopted the FN MAG as the M240 to replace the previous US GPMG (also widely used by allied nations), the M60 machine gun. The US Army uses the M249 - the MINIMI - as its light machine gun/squad automatic weapon, and the M2 machine gun (using the .50 BMG cartridge) is used in the heavy machine gun role.

In the late 1956, the Canadian Military adopted the FN MAG as the C6A1 GPMG along with the purchase of the FNC1 and FNC2's. Even though the C1's and the C2's have been replaced by the C7A1/ C7A2 rifle and the C9A1/ C9A2 LMG, the C6 is still used as a GPMG and is held in such high regard in the Canadian Army that 2 are deployed in each Platoon's Weapon detachment. Due to the need of a Heavy machine gun, the Browning .50 Cal has been brought back into service with the Canadian Army.

Since the late 1950s or early 1960s, the Czechs produced the vz. 59 general purpose machine-gun in both 7.62x54mmR and 7.62 mm NATO (for export models), for which light and heavy barrels were made for differing tactical roles. The approximate Russian equivalent is the PK/PKM family of multi-purpose machine-guns which has been in Russian, and previously Soviet, military service since 1964, and which has been widely exported.

Since 1967, the People's Republic of China has also produced a general purpose machine-gun in 7.62x54mmR as a hybrid weapon derived from several different machine-gun models and with the original model designation of Type 67; since then, second and third modified and improved models of this gun have been made and have been designated Type 67-1 and Type 67-2 respectively.

Heavy machine gun

The M2 Browning machine gun with a tripod weighs 58 kg (128 lb).

Polish partisans firing a Ckm wz.30 (a Polish-made clone of the American Browning M1917) in 1944.

A heavy machine gun refers to either a larger-caliber, high-power machine gun or one of the smaller, medium-caliber (rifle caliber) machine guns meant for prolonged firing from heavy mounts, less mobile, or static positions (or some combination of the two). The latter meaning is generally thought of as an older meaning, and the former as a modern one, but both weapon types have histories extending back to the 1800s. Furthermore, heavier smaller-caliber weapons continue to be used up to the present.

A classic example of a rifle-caliber heavy machine gun would be a water-cooled Maxim machine gun that was belt fed, had a water jacket, was crew served, and mounted on tripod or wheeled mount. Other types used linkable strips (such as the Hotchkiss) or large magazines. A common example of a heavy-caliber machine gun would be the M2 Browning .50-caliber machine gun. Firearms with calibers larger than 13 to 15 mm are generally thought of as autocannons instead of heavy machine guns.

Light machine gun

The FN Minimi, one of the most popular modern 5.56 mm light machine guns among NATO countries

A light machine gun or LMG is a machine gun that is generally lighter than other machine guns of the same period, and is usually designed to be carried by an individual soldier, with or without an assistant. Modern light machine guns often fire smaller-caliber cartridges than medium machine guns, and are usually lighter and more compact. LMGs are often used as squad automatic weapons.

Usually, a light machine gun is intended to act as a support weapon, in that it can generate a greater volume of continuous automatic fire than the usual firearms carried by infantry soldiers, at the cost of greater weight and higher ammunition consumption.

It is possible to fire a light machine gun from the hip or on the move, but they are usually fired from a prone position, especially when using a bipod. Early light machine guns (especially those derived from automatic rifles, such as the M1918 Browning Automatic Rifle) were sometimes magazine-fed. Some LMG's, such as the Russian RPK, are modifications of existing assault rifle designs. Adaptations generally include a larger magazine, heavier barrel to resist overheating, more robust action to support sustained fire, and often a bipod. Modern light machine guns are designed to fire more rounds of a smaller caliber ammunition and as such tend to use a belt of ammunition; this allows them to fire for longer periods of time without the need to reload. Other modern light machine guns, such as the FN Minimi, are capable of firing from either an ammunition belt or a detachable box magazine.

Medium machine gun

A medium machine gun or MMG, in modern terms, usually refers to a belt-fed automatic firearm firing a full-power rifle cartridge and typically weighs from 15 to 40 pounds (6.8 to 18.1 kg). MMGs usually have some type of provision for extended firing, such as a removable or extra-heavy barrel, cooling fins, or a water cooling jacket, but are light enough to be used with a bipod. They occupy a gray area between light machine guns and heavy machine guns.

Two features which have remained somewhat constant, however, are some added ability for greater fire over automatic rifles, and the ability to be used in both light infantry support roles on a bipod, but also on mounts and tripods. While heavy machine guns (HMG) are mostly fired from heavy mounts, and light machine guns (LMG) are usually operated with bipods, MMGs have historically been used in both. Heavy machine guns are either crew-served or mounted, while MMGs are usually operated by one to two soldiers. Light machine guns and automatic rifles are often an individual weapon with a fixed, naked barrel. On the other hand medium machine guns have usually had more endurance of some sort, such as the aforementioned heavier barrel, barrel-change, fins etc.

Squad automatic weapon

A squad automatic weapon (SAW, also known as section automatic weapon or light support weapon) is a light or general purpose machine gun, usually equipped with a bipod and firing a rifle-caliber cartridge. A SAW is used to provide suppressive fire for an infantry squad or section, and typically uses the same ammunition as the assault rifles carried by other members of the unit, simplifying military logistics.

The basic use of this weapon is to force enemy troops to take cover and reduce the effectiveness of their return fire while friendly troops advance, increasing the likelihood of a successful attack against an enemy position. SAWs must therefore be light enough for an individual soldier to carry and fire. SAWs may also be used in defending friendly positions, but cannot provide a field of fire as effective as that of a tripod-mounted machine gun.

Many SAWs (such as the RPK-74 and L86) are modified assault rifles. The most common SAWs in use today are derived from two basic patterns: RPK or FN Minimi. One of the first weapons designed for this role was the M1918 Browning Automatic Rifle, which, though having a limited magazine capacity, was still higher than the typical infantry rifle, and it gave the infantry a base of fire weapon that was more suited to maneuver warfare than the bulkier machine guns of the period, such as the M1919 Browning machine gun.

Minigun

The minigun is a multi-barrel machine gun with a high rate of fire (several thousand rounds per minute), employing Gatling-style rotating barrels and an external power source. In popular culture, the term "minigun" has come to refer to any externally-powered Gatling gun of rifle caliber, though the term is sometimes used to refer to guns of similar rates of fire and configuration, regardless of power source and caliber. Specifically, minigun refers to a single weapon, originally produced by General Electric. The "mini" of the name is in comparison to designs that use a similar firing mechanism but 20 mm or larger shells, such as General Electric's earlier M61 Vulcan.

• Design and variants

The basic weapon is a 6-barrel, air-cooled, and electrically driven machine gun. The electric drive rotates the weapon within its housing, with a rotating firing pin assembly and rotary chamber. The minigun's multibarrel design helps prevent overheating, but also serves other functions. Multiple barrels allow for a greater capacity for a high firing rate, since the serial process of firing/extraction/loading is taking place in all barrels simultaneously. Thus, as one barrel fires, two others are in different stages of shell extraction and another three are being loaded. The minigun is composed of multiple closed-bolt rifle barrels arranged in a circular housing. The barrels are rotated by an external power source: usually electric, pneumatic, or hydraulic. Other rotating-barrel cannons are powered by the gas pressure or recoil energy of fired cartridges. A gas-operated variant, designated the XM133, was also developed, but was not put into production.

While the weapon can feed from linked ammunition, it requires a delinking feeder to strip the links as the rounds are introduced to the chambers. The original unit was designated MAU-56/A, but has since been replaced by an improved MAU-201/A unit.

G.E.'s minigun is in use in all major branches of the US military, under a number of designations. The basic fixed armament version was given the designation M134 by the U.S. Army, while the exact same weapon was designated GAU-2/A by the U.S. Air Force. The USAF weapon has three subvariants, while the US Army weapon appears to have incorporated any new improvements without a change in designation. Available sources show a relation between both M134 and GAU-2/A and M134 and GAU-2B/A. A separate variant, designated XM196, with an added ejection sprocket was developed specifically for the XM53 Armament Subsystem on the AH-56 Cheyenne helicopter.

Another variant was developed by the U.S. Air Force specifically for flexible installations, at the time primarily for the UH-1N helicopter, as the GAU-17/A. The primary end users of the GAU-17/A have been the U.S. Navy and the U.S. Marine Corps, who mount them on as defensive armament on a number of helicopters and surface ships. The weapon is part of both the A/A49E-11 armament system on the UH-1N and A/A49E-13 armament subsystem on the HH-60H aircraft. The weapons on these systems feature a selectable fire rate of either 2,000 or 4,000 rpm. There is mention of a possible GAUSE-17 designation (GAU-Shipboard Equipment-17), in reference to the system when mounted on surface ships, though this would not follow the official ASETDS designation system's format.

Other manufacturers in the United States also produce Miniguns with various refinements of their own, including Dillon Aerospace (the "M134D"), and Garwood Industries (the "M134G").

Military and civilian handguns

• Handgun
  • Captive bolt pistol
  • Hand cannon
  • Machine pistol
  • Pistol
    • Howdah pistol
    • Junk gun
    • Mousegun
    • Pocket pistol
  • Revolver

Handgun

designed to be held in the hand when used. This characteristic differentiates handguns as a general class of firearms from their larger counterparts: long guns such as rifles and shotguns, mounted weapons such as machine guns and autocannons, and larger weapons such as artillery.

Some handgun subtypes include single-shot pistols, revolvers, semi-automatic pistols, and fully automatic, or machine pistols.

The overlapping variations in meaning of the words "pistol" and "handgun" are discussed below.

• Nomenclature variations

Multiple senses of the word "pistol"

The word "pistol" is often synonymous with the word "handgun". Some handgun experts make a technical distinction that views pistols as a subset of handguns. In American usage, the term "pistol" refers to a handgun whose chamber is integral with the barrel, making pistols distinct from the other main type of handgun, the revolver, which has a revolving cylinder containing multiple chambers. However, Commonwealth usage makes no distinction at a technical level—"pistol" may refer to revolvers, semi-automatics, or muzzle-loading/cap-&-ball handguns. For example, the official designation of the Webley Mk VI was "Pistol, Revolver, Webley No. 1 Mk VI", and the designation "Pistol No. 2 Mk I" was used to refer to both the Enfield Revolver and the later Browning Hi-Power semi-automatic.

The first pistols were made as early as the 15th century, however the creator is unknown. By the 18th century, the term came to be used often to refer to handheld firearms. Practical revolver designs appeared in the 19th century, and it was in that century that the (sometimes-observed) technical differentiation in usage of the words "pistol" and "revolver" developed.

Etymology of "pistol"

Hand Cannon from the Chinese Yuan Dynasty (1271-1368).

The word "pistol" is derived from the French pistole (or pistolet), which has these possible origins:

• From the Czech pistole and this one from the Czech píšťala (flute or pipe, referring to the shape of a Hussite firearm), via Middle High German pischulle and Middle French pistole.
• From the city of Pistoia, Italy, where hand-held guns (designed to be fired from horseback) were first produced in the 1540s.
• That early pistols were carried by cavalry in holsters hung from the pommel (or pistallo in medieval French) of a horse's saddle.

Captive bolt pistol

A captive bolt pistol (also variously known as a cattle gun, stunbolt gun, bolt gun, or stunner) is a device used for stunning beasts prior to slaughter. Proper stunning is essential to prevent the pain and suffering of the beast during the bleeding (exsanguination) process (which is itself necessary to prevent meat spoilage) during butchering. The principle behind captive bolt stunning is a forceful strike on the forehead using a bolt to induce unconsciousness. The bolt may or may not destroy part of the brain.

The bolt is a heavy rod made of non-rusting alloys, such as stainless steel. It is held in position inside the barrel of the stunner by means of rubber washers. The bolt is usually not visible in a stunner in good condition. The bolt is actuated by a trigger pull and is propelled forward by compressed air or by the discharge of a blank round ignited by a firing pin. After striking a shallow but forceful blow on (or through) the forehead of the beast, spring tension causes the bolt to recoil back into the barrel.

• Variations

The captive bolt pistols are of three types: penetrating, non-penetrating, and free bolt.

In the penetrating type, the stunner uses a pointed bolt which is propelled by pressurized air or a blank cartridge. The bolt penetrates the skull of the beast, enters the cranium, and catastrophically damages the cerebrum and part of the cerebellum. Due to concussion, destruction of vital centres of brain and an increase in intracranial pressure, the beast loses consciousness. This method is currently the most effective and widely used type of stunning, since it physically destroys brain matter (increasing the probability of a successful stun), while also leaving the brain stem intact (thus ensuring the heart continues to beat, facilitating a successful bleed). One disadvantage of this method is that brain matter is allowed into the blood stream, possibly contaminating other tissue with bovine spongiform encephalopathy (B.S.E.).

The action of a non-penetrating stunner is similar, but the bolt is blunt with a mushroom-shaped tip. The bolt strikes the forehead with great force and immediately retracts. This concussion is responsible for the unconsciousness of the animal. This type of stunner is less reliable at causing immediate and permanent unconsciousness than penetrating types; however, it has undergone a resurgence of popularity due to concerns about mad cow disease. In the European Union, this captive bolt design is required for slaughter of animals that will be used for pharmaceutical manufacture.

The free bolt stunner is used for the emergency in-the-field euthanasia of large farm-beasts who cannot be restrained. It differs from a true captive bolt gun in that the projectile is not retractable; it is similar in operation to a powder-actuated nail gun or conventional firearm. Capable of firing only when pressed firmly against a surface (typically the beast's forehead), the device fires a small projectile through the beast's skull. The veterinarian can then either leave the beast to expire from the projectile wound, or administer lethal drugs.

Machine pistol

A machine pistol is a handgun-style, magazine-fed and self-loading firearm, capable of fully automatic or burst fire, and normally chambered for pistol cartridges. The term is a literal translation of Maschinenpistole, the German term for a submachine gun. While the dividing line between machine pistols and compact submachine guns is hard to draw, the term submachine gun usually refers to larger automatic firearms. Typically, a submachine gun's operating mechanism is scaled down from that of a full-sized machine gun, while a machine pistol is built up from a semi-automatic pistol design.

Machine pistols are used by tactical police units such as SWAT teams or hostage rescue teams inside buildings and other cramped spaces. Machine pistols are also used by government security service bodyguards for VIPs and heads of state who need a weapon that can be concealed under clothing. They are also occasionally issued to undercover operatives in anti-drug units such as the US Drug Enforcement Administration, who need a small, concealable weapon with a high rate of fire. In a military setting, machine pistols are issued as personal defense sidearms to paratroopers, artillery crews, helicopter crews or tank crews. They have also been used in close quarters combat (CQC) settings where a small weapon is needed (e.g. by special forces attacking buildings or tunnels).

Semi-automatic Pistol

A semi-automatic pistol is a type of handgun that can be fired in semi-automatic mode, firing one cartridge for each pull of the trigger. This type of firearm uses a single chamber and a single barrel, which remain in a fixed linear orientation relative to each other while being fired and reloaded semi-automatically. Some terms that have been, or still are, used as synonyms for semi-automatic pistol are automatic pistol, autopistol, self-loading pistol, and selfloader.

Springfield Armory M1911A1 single-action .45 ACP semi-automatic pistol

Smith & Wesson double-action .45 ACP semi-automatic compact pistol

Contemporary Polish WIST-94 semi-automatic pistol.

Overview

A semi-automatic pistol functions by using the energy from the recoil of a single round of ammunition to extract and eject a fired cartridge from the pistol's chamber and load an unfired round from a magazine into the chamber for the next shot.

Most types of semi-automatic pistols rely on a removable magazine for supplying new ammunition to reload the chamber to be able to fire the gun again. The removable magazine is typically located inside a hand grip. Typically, the first round is manually loaded into the chamber by pulling back and releasing ("racking") the slide mechanism, after which the recoil operation of the handgun when fired automatically extracts, ejects, and reloads the chamber. This mode of operation generally allows for faster reloading and storing a larger number of cartridges than a revolver, although semi-automatic pistols are potentially more prone to malfunctions than revolvers due to their more complex design and mechanism.

Some modern semi-automatic pistols are double action only (DAO); that is, once a round is chambered, each trigger pull will cock the hammer, striker, or firing pin, and will additionally release the same to fire a cartridge in one continuous motion. Each pull of the trigger on a DAO semi-automatic pistol requires the same amount of pressure. The Kel-Tec P-32 is an example of a DAO action. DAO semi-automatic pistols are most generally recommended only in the smaller, self-defense, concealable pistols, rather than in target or hunting pistols (a notable exception being Glock-brand competition pistols such as the G34 and G35 which are DAO, yet designed with low-strength sear connectors resulting in lightened trigger pulls to improve a shooter's accuracy).

Standard modern semi-automatic pistols are usually double action (DA), also sometimes known as double-action/single-action (DA/SA.) In this design, the hammer or striker may be either thumb-cocked or activated by pulling the trigger when firing the first shot. The hammer or striker is re-cocked automatically during each firing cycle. In double-action (DA) pistols, the first pull of the trigger requires roughly twice as much pressure as subsequent firings, since the first pull of the trigger also cocks the hammer (if not already cocked by hand). The Beretta 92F/FS, a full-sized, service, semi-automatic pistol is an example of this style of action. A common mode of carry for DA semi-automatic pistols is with the magazine full, a round chambered, and the gun holstered and uncocked with the external safety unengaged or off.

An alternative carry mode, and the mode often used by single-action pistols, is with the magazine partially full, a round chambered, and the gun holstered, and cocked with the external safety engaged or on. In contrast, a single-action (SA), semi-automatic pistol must be cocked by first operating the slide or bolt, or, if a round is already chambered, by cocking the hammer manually. The famed Colt M1911 is an example of this style of action. All SA semi-automatic pistols exhibit this feature, and automatically cock the hammer when the slide is first "racked" to chamber a round.

The normal mode of carrying an SA semi-automatic pistol is Condition 1, popularly known as cocked and locked (see photo of Springfield Armory M1911A1 above). Condition 1 (a term popularized by Colonel Jeff Cooper) refers to having the magazine full, a round chambered, the hammer fully cocked, and the thumb safety engaged or on, at least for right-handed users. For many single-action, semi-automatic pistols, this procedure works well only for right-handed users, as the thumb safety is located on the left side of pistol and is easily accessible only for those who are holding the pistol in the right hand.

On many SA semi-automatic pistols, there is also a hammer position known as "half-cocked.". Squeezing the trigger will not fire the gun when it is in the half-cocked position, and neither will dropping the gun in this state cause an accidental discharge. During WWII in the Pacific Theater, an unofficial and unapproved carry mode for the SA M1911 by left-handed US soldiers in combat was carrying the gun with the magazine full, a round chambered, the action in half-cocked position, and the thumb safety (accessible only to right-handed users) positioned in the off (or ready-to-fire) mode. The primary advantage of the half-cocked position versus the uncocked position in that particular scenario was added sound suppression, a secondary advantage being the avoidance of accidental discharges if the gun were accidentally dropped. The half cock was revised by Colt in the 1970s and subsequently other manufacturers - the hammer will fall from half cock if the trigger is pulled on most newer 1911 type guns.

Cocking the gun from uncocked to fully cocked was much noisier than turning the safety off for right-handed users, or cocking the gun from half cocked to fully cocked for left-handed users. In general, however, single-action, semi-automatic pistols should never be carried cocked with the safety off. Many modern SA semi-automatic pistols have had their safety mechanisms redesigned to provide a thumb safety on both sides of the pistol, thereby better meeting the needs of left-handed as well as right-handed users.

There also have been notable semi-automatic pistol designs with different traits than those generally described here, including those with a magazine fed with a stripper clip, and those with non-removable (sometimes called blind-box) magazines. These designs are rarely used in modern semi-automatic pistols. The Model C96, or "Broomhandle" Mauser, in its original configuration, has a fixed, non-removable magazine located in front of the trigger, which is loaded directly through the breech from the top of the pistol, in contrast to most contemporary pistol designs.

Semi-automatic pistols utilize one firing chamber that remains fixed in a constant linear position relative to the gun barrel. In contrast, although double-action revolvers can also be fired semi-automatically, their rounds are not fired from a single chamber, but rather are fired from each of 5 to 10 chambers, with 6 chambers being the most common, that are rotated into linear alignment with the barrel's position in turn just prior for each shot fired.

The language surrounding automatic, semi-automatic, self-loading, etc., often causes confusion due to differences in technical usage between different countries and differences in popular usage. For example, an automatic pistol technically refers to a machine pistol, although in popular American usage it is also used as a synonym for a semi-automatic pistol. In the case of pistols, an 'automatic pistol', a 'semi-automatic pistol', or a 'self-loading pistol', all usually imply a handgun that is semi-automatic, self-loading, and magazine-fed with a magazine that is removable, producing one shot fired for each trigger pull. The term pistol may refer to handguns in general, or may be used to differentiate (semi-automatic) pistols from revolvers.

Howdah pistol

A Howdah Pistol was a large-calibre handgun, often with two or four barrels, used in India and Africa during the period of British Colonial rule in the mid-to-late-nineteenth and early-twentieth centuries, typically for defence against tigers, lions, and other large, dangerous animals that might be encountered in the jungles or remote areas. Multi-barrelled designs were initially favoured for Howdah pistols because they offered faster reloading than was possible with contemporary revolvers, which had to be loaded and unloaded through a gate in the side of the frame.

The name "Howdah pistol" comes from the sedan chair- known as a Howdah- which is mounted on the back of an elephant; hunters, especially during the period of the British Raj in India used howdahs as a platform for hunting wild animals and needed large-calibre side-arms to protect themselves, the elephant, and their passengers from animal attacks at close range.

The first Howdah pistols were little more than sawn-off rifles, typically in .577 Snider or .577/450 Martini-Henry calibre, but later on English firearms makers did manufacture specially designed Howdah pistols in both rifle calibres and more conventional handgun calibres such as .455 Webley and .476 Enfield. As a result, the name "Howdah pistol" is often applied to a number of English multi-barrelled handguns such as the Lancaster pistol (available in a variety of calibres from .380" to .577"), and various .577 calibre revolvers produced in England and Europe for a brief time in the mid-late 19th century.

Even though Howdah pistols were designed for use in the “gravest extreme” against dangerous game (such as tigers), British officers adopted them in other far-flung outposts of the British Empire, although by the late 19th century, top-break revolvers in more practical calibres (such as .455 Webley) had become much more widespread,, removing much of the traditional market for Howdah pistols.

In the movie The Ghost and the Darkness the character Remington (Michael Douglas) carries a unique superposed double barrel Howdah pistol.

Saturday night special

The phrase Saturday night special is pejorative slang used in the United States and Canada for any inexpensive handgun. Saturday night specials have been defined as compact, inexpensive handguns with low perceived quality; however, there is no official definition of "Saturday night special" under federal law, though some states define "Saturday Night Special" or "Junk Guns" by means of composition or materials strength. Low cost and availability make them attractive to low-income buyers despite their shortcomings.

Controversy

Laws prohibiting or regulating the purchase of inexpensive handguns such as Saturday Night Specials are controversial in the United States. The two primary areas of contention relate to the availability of guns and the effect of purchase price upon the demographic of who buys them.

Availability

Some see the availability of handguns as a threat to the community. In 2003, the NAACP filed suit against 45 gun manufacturers for creating what it called a "public nuisance" through the "negligent marketing" of handguns, which included models commonly described as Saturday Night Specials. The suit alleged that handgun manufacturers and distributors were guilty of marketing guns in a way that encouraged violence in black and Hispanic neighborhoods. "The gun industry has refused to take even basic measures to keep criminals and prohibited persons from obtaining firearms," NAACP President/CEO Kweisi Mfume said. "The industry must be as responsible as any other and it must stop dumping firearms in over-saturated markets. The obvious result of dumping guns is that they will increasingly find their way into the hands of criminals." The suit was dismissed by U.S. District Judge Jack B. Weinstein, who ruled that members of the NAACP were not "uniquely harmed" by illegal use of firearms and therefore had no standing to sue.

Economic Class

Because the price of a firearm helps to determine who is able to buy it, the elimination of inexpensive firearms has a direct effect upon those of lesser means. Roy Innis, president of the activist group Congress on Racial Equality, said "To make inexpensive guns impossible to get is to say that you're putting a money test on getting a gun. It's racism in its worst form." (The Congress on Racial Equality filed as an amicus curiae in a 1985 suit challenging Maryland's Saturday night special/low-caliber handgun ban.) The Wright and Rossi National Institute of Justice study (p.238) concluded: "The people most likely to be deterred from acquiring a handgun by exceptionally high prices or by the nonavailability of certain kinds of handguns are not felons intent on arming themselves for criminal purposes (who can, if all else fails, steal the handgun they want), but rather poor people who have decided they need a gun to protect themselves against the felons but who find that the cheapest gun in the market costs more than they can afford to pay."

Mousegun

A mousegun intended for is most often considered a category of small revolver, or semi-automatic handgunself defense; typically such small pistols are of .380 ACP (9mm Short) caliber or less, with .32 ACP and .22 Long Rifle calibers also being common. The term is used to describe a class of small handguns.

Terminology

Among mousegun users, the term mousegun itself is not usually considered to be pejorative, but is instead affectionately used. Manufacturers of these guns however generally label them as "ultra-compact", avoiding the derogatory connotation given by users of larger-caliber, larger-size guns, and also differentiating them from "sub-compact" models such as the Glock 26 and 30, which have a similar role of deep concealment, but fire larger "defense caliber" cartridges between 9x19mm Parabellum and .45 ACP and are therefore slightly larger themselves.

It should be mentioned that those who favor larger, heavier handguns (not necessarily of larger caliber) do often use the term mousegun for any small caliber firearm in a disparaging way, generally for guns they see as intended for use in a military or self defense role where power should be considered more important.

Among those who prefer larger, heavier guns, the term mousegun is sometimes applied to junk guns, especially those in .22 Long Rifle or .25 ACP.

Among those who prefer larger, heavier guns, it is noteworthy to realize that .22 caliber pistols (and even rifles) that are intended for target shooting, plinking, or small game hunting are not considered mouseguns. In this usage, there is widespread agreement, even among those who favor the use of mouseguns for use in deeply-concealed carry; full-size handguns and rifles, despite firing small caliber bullets, are not mouseguns.

Pocket Pistol

A pocket pistol is an American term for any small, pocket-sized semi-automatic pistol or, less-popular, any other handgun (e.g., derringer, or small revolver) of (most commonly) small caliber, suitable for concealed carry in either a front or rear pocket of a pair of trousers, or in an exterior coat pocket. Some consider the term solely applicable for hammerless handguns that are striker-fired in semi-automatic blowback configurations, only.^[1] However, with the advent of newer and smaller double action only (DAO) semi-automatic pistol designs, some locked breech concealed-hammer pistol designs are now also called pocket pistols. Well-made, more-expensive pocket pistols are called mouseguns.

Example of a pocket pistol

In general use, the term pocket pistol is not considered a pejorative term.

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.