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A machine gun is a
fully automatic An automatic firearm is an auto-loading firearm that continuously chambers and fires rounds when the trigger mechanism is actuated. The action of an automatic firearm is capable of harvesting the excess energy released from a previous discha ...
,
rifled In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the ...
autoloading
firearm A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see Legal definitions). The first firearms originated in 10th-century China, when bamboo tubes ...
designed for sustained
direct fire Direct fire or line-of-sight fire refers to firing of a ranged weapon whose projectile is launched directly at a target within the line-of-sight of the user. The firing weapon must have a sighting device and an unobstructed view to the target, w ...
with
rifle cartridge A rifle cartridge is a firearm cartridge primarily designed and intended for use in a rifle/carbine, or machine gun. Types Full-powered A full-powered cartridge is a rifle cartridge used interchangeably between service rifles, sniper rifle ...
s. Other
automatic firearm An automatic firearm is an auto-loading firearm that continuously chambers and fires rounds when the trigger mechanism is actuated. The action of an automatic firearm is capable of harvesting the excess energy released from a previous discha ...
s such as
automatic shotguns Automatic may refer to: Music Bands * Automatic (band), Australian rock band * Automatic (American band), American rock band * The Automatic, a Welsh alternative rock band Albums * ''Automatic'' (Jack Bruce album), a 1983 electronic roc ...
and
automatic rifle An automatic rifle is a type of autoloading rifle that is capable of fully automatic fire. Automatic rifles are generally select-fire weapons capable of firing in semi-automatic and automatic firing modes (some automatic rifles are capable of ...
s (including assault rifles and
battle rifle A battle rifle is a service rifle chambered to fire a fully powered cartridge. The term "battle rifle" is a retronym created largely out of a need to better differentiate the intermediate-powered assault rifles (e.g. the StG-44, AK-47, M16, ...
s) are typically designed more for firing short bursts rather than continuous
firepower Firepower is the military capability to direct force at an enemy. (It is not to be confused with the concept of rate of fire, which describes the cycling of the firing mechanism in a weapon system.) Firepower involves the whole range of potenti ...
, and are not considered true machine guns. As a class of military
kinetic projectile A kinetic energy weapon (also known as kinetic weapon, kinetic energy warhead, kinetic warhead, kinetic projectile, kinetic kill vehicle) is a weapon based solely on a projectile's kinetic energy instead of an explosive or any other kind of payl ...
weapon, machine guns are designed to be mainly used as infantry support weapons and generally used when attached to a
bipod A bipod is a V-shaped portable attachment that helps support and steady a device, usually a weapon such as a long gun or a mortar. The term comes from the Latin prefix ''bi-'' and Greek root ''pod'', meaning "two" and "foot" respectively. Bip ...
or
tripod A tripod is a portable three-legged frame or stand, used as a platform for supporting the weight and maintaining the stability of some other object. The three-legged (triangular stance) design provides good stability against gravitational loads ...
, a fixed mount or a heavy
weapons platform A weapons platform is generally any structure, vehicle or mechanism on which a weapon can be installed (via various mounting mechanisms) for optimal stability and performance. The mounted weapons, the platform and all other associated supportin ...
for stability against
recoil Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force r ...
s. Many machine guns also use belt feeding and
open bolt A firearm is said to fire from an open bolt if, when ready to fire, the bolt and working parts are held to the rear of the receiver, with no round in the chamber. When the trigger is actuated, the bolt travels forward, feeds a cartridge from t ...
operation, features not normally found on other infantry firearms. Machine guns can be further categorized as
light machine gun A light machine gun (LMG) is a light-weight machine gun designed to be operated by a single infantryman, with or without an assistant, as an infantry support weapon. LMGs firing cartridges of the same caliber as the other riflemen of the ...
s,
medium machine gun A medium machine gun (MMG), in modern terms, usually refers to a belt-fed machine gun firing a full-powered rifle cartridge, and is considered "medium" in weight (). Medium machine guns are light enough to be infantry-portable (as opposed to a h ...
s,
heavy machine gun A heavy machine gun (HMG) is significantly larger than light, medium or general-purpose machine guns. HMGs are typically too heavy to be man-portable (carried by one person) and require mounting onto a weapons platform to be operably stable or ...
s,
general purpose machine gun A general-purpose machine gun (GPMG) is an air-cooled, usually belt-fed machine gun that can be adapted flexibly to various tactical roles for light and medium machine guns. A GPMG typically features a quick-change barrel design calibered f ...
s and
squad automatic weapon A squad automatic weapon (SAW), also known as a section automatic weapon or light support weapon (LSW), is a man-portable automatic firearm attached to infantry squads or sections as a source of rapid direct firepower. Weapons fulfilling t ...
s. Similar automatic firearms of caliber or more are classified as
autocannon An autocannon, automatic cannon or machine cannon is a fully automatic gun that is capable of rapid-firing large-caliber ( or more) armour-piercing, explosive or incendiary shells, as opposed to the smaller-caliber kinetic projectiles (bul ...
s, rather than machine guns.


Modern overview

Unlike
semi-automatic firearm 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 fol ...
s, which require one trigger pull per round fired, a machine gun is designed to continue firing for as long as the trigger is held down. Nowadays, the term is restricted to relatively heavy
crew-served weapon A crew-served weapon is any weapon system that is issued to a crew of two or more individuals performing the same or separate tasks to run at maximum operational efficiency, as opposed to an individual-service weapon, which only requires one pe ...
s, able to provide continuous or frequent bursts of automatic fire for as long as ammunition feeding is replete. Machine guns are used against
infantry Infantry is a military specialization which engages in ground combat on foot. Infantry generally consists of light infantry, mountain infantry, motorized infantry & mechanized infantry, airborne infantry, air assault infantry, and mar ...
, low-flying
aircraft An aircraft is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or by using the Lift (force), dynamic lift of an airfoil, or in ...
, small
boat A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size, shape, cargo or passenger capacity, or its ability to carry boats. Small boats are typically found on i ...
s and lightly/un
armored Armour (British English) or armor (American English; see spelling differences) is a covering used to protect an object, individual, or vehicle from physical injury or damage, especially direct contact weapons or projectiles during combat, or f ...
land vehicle A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), wat ...
s, and can provide
suppressive fire In military science, suppressive fire is "fire that degrades the performance of an enemy force below the level needed to fulfill its mission". When used to protect exposed friendly troops advancing on the battlefield, it is commonly called cove ...
(either directly or indirectly) or enforce
area denial An area denial weapon is a defensive device used to prevent an adversary from occupying or traversing an area of land, sea or air. The specific method used does not have to be totally effective in preventing passage (and sometimes is not) as lon ...
over a sector of land with grazing fire. They are commonly mounted on fast attack vehicles such as
technicals Technicals may refer to: * Technical (vehicle), an improvised fighting vehicle often used in civil conflict * TECHNICALS, a clothing brand owned by Blacks Leisure Group See also * Technical (disambiguation) * Cambridge Technicals Cambridge Tech ...
to provide heavy mobile firepower, armored vehicles such as
tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful ...
s for engaging targets too small to justify the use of the primary weaponry or too fast to effectively engage with it, and on aircraft as defensive armament or for strafing ground targets, though on fighter aircraft true machine guns have mostly been supplanted by large-caliber rotary guns. Some machine guns have in practice sustained fire almost continuously for hours; other automatic weapons overheat after less than a minute of use. Because they become very hot, the great majority of designs fire from an
open bolt A firearm is said to fire from an open bolt if, when ready to fire, the bolt and working parts are held to the rear of the receiver, with no round in the chamber. When the trigger is actuated, the bolt travels forward, feeds a cartridge from t ...
, to permit air cooling from the
breech Breech may refer to: * Breech (firearms), the opening at the rear of a gun barrel where the cartridge is inserted in a breech-loading weapon * breech, the lower part of a pulley block * breech, the penetration of a boiler where exhaust gases leave ...
between bursts. They also usually have either a barrel cooling system, slow-heating heavyweight barrel, or removable barrels which allow a hot barrel to be replaced. Although subdivided into "
light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 t ...
", "
medium Medium may refer to: Science and technology Aviation * Medium bomber, a class of war plane * Tecma Medium, a French hang glider design Communication * Media (communication), tools used to store and deliver information or data * Medium ...
", "
heavy Heavy may refer to: Measures * Heavy (aeronautics), a term used by pilots and air traffic controllers to refer to aircraft capable of 300,000 lbs or more takeoff weight * Heavy, a characterization of objects with substantial weight * Heavy, ...
" or " general-purpose", even the lightest machine guns tend to be substantially larger and heavier than standard infantry arms. Medium and heavy machine guns are either mounted on a
tripod A tripod is a portable three-legged frame or stand, used as a platform for supporting the weight and maintaining the stability of some other object. The three-legged (triangular stance) design provides good stability against gravitational loads ...
or on a vehicle; when carried on foot, the machine gun and associated equipment (tripod, ammunition, spare barrels) require additional crew members. Light machine guns are designed to provide mobile fire support to a squad and are typically air-cooled weapons fitted with a box magazine or drum and a bipod; they may use full-size rifle rounds, but modern examples often use intermediate rounds. Medium machine guns use full-sized rifle rounds and are designed to be used from fixed positions mounted on a tripod. The heavy machine gun is a term originating in World War I to describe heavyweight medium machine guns and persisted into World War II with Japanese
Hotchkiss M1914 The Mle 1914 Hotchkiss machine gun chambered for the 8mm Lebel cartridge became the standard machine gun of the French Army during the latter half of World War I. It was manufactured by the French arms company Hotchkiss et Cie, which had been e ...
clones; today, however, it is used to refer to automatic weapons with a caliber of at least but less than 20 mm. A general-purpose machine gun is usually a lightweight medium machine gun that can either be used with a bipod and drum in the light machine gun role or a tripod and belt feed in the medium machine gun role. Machine guns usually have simple iron sights, though the use of optics is becoming more common. A common aiming system for direct fire is to alternate solid ("ball") rounds and
tracer ammunition Tracer ammunition (AMO) (Tracers) are bullets or cannon-caliber projectiles that are built with a small pyrotechnic charge in their base. When fired, the pyrotechnic composition is ignited by the burning powder and burns very brightly, making ...
rounds (usually one tracer round for every four ball rounds), so shooters can see the trajectory and "walk" the fire into the target, and direct the fire of other
soldier A soldier is a person who is a member of an army. A soldier can be a Conscription, conscripted or volunteer Enlisted rank, enlisted person, a non-commissioned officer, or an Officer (armed forces), officer. Etymology The word ''soldier'' deri ...
s. Many
heavy machine gun A heavy machine gun (HMG) is significantly larger than light, medium or general-purpose machine guns. HMGs are typically too heavy to be man-portable (carried by one person) and require mounting onto a weapons platform to be operably stable or ...
s, such as the
Browning M2 The M2 machine gun or Browning .50 caliber machine gun (informally, "Ma Deuce") is a heavy machine gun that was designed towards the end of World War I by John Browning. Its design is similar to Browning's earlier M1919 Browning machine gun, ...
.50 caliber This is a list of firearm cartridges which have bullets in the to caliber range. *''Length'' refers to the cartridge case Case or CASE may refer to: Containers * Case (goods), a package of related merchandise * Cartridge case or casing, a ...
machine gun, are accurate enough to engage targets at great distances. During the
Vietnam War The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
,
Carlos Hathcock Carlos Norman Hathcock II (May 20, 1942 – February 22, 1999) was a United States Marine Corps (USMC) sniper with a service record of 93 confirmed kills. Hathcock's record and the extraordinary details of the missions he undertook made him a l ...
set the record for a long-distance shot at with a .50 caliber heavy machine gun he had equipped with a
telescopic sight A telescopic sight, commonly called a scope informally, is an optical sighting device based on a refracting telescope. It is equipped with some form of a referencing pattern – known as a '' reticle'' – mounted in a focally appropriate ...
.Henderson, Charles (2005). ''Marine Sniper''. Berkley Caliber. . This led to the introduction of .50 caliber anti-materiel sniper rifles, such as the
Barrett M82 The Barrett M82 (standardized by the U.S. military as the M107) is a recoil-operated, semi-automatic anti-materiel rifle developed by the American company Barrett Firearms Manufacturing. Also called the Light Fifty (due to its chambering of ...
. Other automatic weapons are subdivided into several categories based on the size of the bullet used, whether the
cartridge Cartridge may refer to: Objects * Cartridge (firearms), a type of modern ammunition * ROM cartridge, a removable component in an electronic device * Cartridge (respirator), a type of filter used in respirators Other uses * Cartridge (surname), a ...
is fired from a
closed bolt A semi or full-automatic firearm which is said to fire from a closed bolt is one where, when ready to fire, a round is in the chamber and the bolt and working parts are forward. When the trigger is pulled, the firing pin or striker fires the ...
or an
open bolt A firearm is said to fire from an open bolt if, when ready to fire, the bolt and working parts are held to the rear of the receiver, with no round in the chamber. When the trigger is actuated, the bolt travels forward, feeds a cartridge from t ...
, and whether the
action Action may refer to: * Action (narrative), a literary mode * Action fiction, a type of genre fiction * Action game, a genre of video game Film * Action film, a genre of film * ''Action'' (1921 film), a film by John Ford * ''Action'' (1980 fil ...
used is locked or is some form of blowback. Fully automatic firearms using pistol-caliber ammunition are called
machine pistol A machine pistol is an autoloading pistol capable of fully automatic fire. The term can also be used to describe a stockless handgun-style submachine gun. The term is a calque of ''Maschinenpistole'', the German word for submachine guns. Ma ...
s or submachine guns largely on the basis of size; those using shotgun cartridges are almost always referred to as
automatic shotgun An automatic shotgun is an automatic firearm that fires shotgun shells (thereby making it a shotgun) and uses some of the energy of each shot to automatically cycle the action and load a new round. It will fire repeatedly until the trigger is rel ...
s. The term
personal defense weapon Personal defense weapons (PDWs) are a class of firearms intended for self-defense and security rather than warfare and infantry. Most PDWs fire a small-caliber (less than ), centerfire bottleneck cartridge resembling a scaled-down intermedia ...
(PDW) is sometimes applied to weapons firing dedicated armor-piercing rounds which would otherwise be regarded as machine pistols or SMGs, but it is not particularly strongly defined and has historically been used to describe a range of weapons from ordinary SMGs to compact assault rifles.
Selective fire Selective fire is the capability of a weapon to be adjusted to fire in semi-automatic, fully automatic, and/or burst mode. The modes are chosen by means of a selector switch, which varies depending on the weapon's design. Some selective-fire w ...
rifles firing a full-power rifle cartridge from a closed bolt are called
automatic rifle An automatic rifle is a type of autoloading rifle that is capable of fully automatic fire. Automatic rifles are generally select-fire weapons capable of firing in semi-automatic and automatic firing modes (some automatic rifles are capable of ...
s or
battle rifle A battle rifle is a service rifle chambered to fire a fully powered cartridge. The term "battle rifle" is a retronym created largely out of a need to better differentiate the intermediate-powered assault rifles (e.g. the StG-44, AK-47, M16, ...
s, while rifles that fire an intermediate cartridge are called assault rifles. Assault rifles are a compromise between the size and weight of a pistol-caliber submachine gun and a full-size battle rifle, firing intermediate cartridges and allowing semi-automatic and burst or full-automatic fire options (selective fire), sometimes with both of the latter presents.


Operation

Many machine guns are of the locked breech type, and follow this cycle: * Pulling (manually or electrically) the bolt assembly/bolt carrier rearward by way of the cocking lever to the point bolt carrier engages a sear and stays at rear position until trigger is activated making bolt carrier move forward * Loading fresh round into chamber and locking bolt * Firing round by way of a firing pin or striker (except for aircraft medium calibre using electric ignition primers) hitting the primer that ignites the powder when bolt reaches locked position. * Unlocking and removing the spent case from the chamber and ejecting it out of the weapon as bolt is moving rearward * Loading the next round into the firing chamber. Usually, the recoil
spring Spring(s) may refer to: Common uses * Spring (season), a season of the year * Spring (device), a mechanical device that stores energy * Spring (hydrology), a natural source of water * Spring (mathematics), a geometric surface in the shape of a h ...
(also known as main spring) tension pushes bolt back into battery and a
cam Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bin ...
strips the new round from a feeding device, belt or box. *Cycle is repeated as long as the trigger is activated by operator. Releasing the trigger resets the trigger mechanism by engaging a sear so the weapon stops firing with bolt carrier fully at the rear. The operation is basically the same for all locked breech automatic firearms, regardless of the means of activating these mechanisms. There are also multi-chambered formats, such as
revolver cannon A revolver cannon is a type of autocannon, commonly used as an aircraft gun. It uses a cylinder with multiple chambers, like those of a revolver handgun, to speed up the loading-firing-ejection cycle. Some examples are also power-driven, to fur ...
, and some types, such as the
Schwarzlose machine gun The Maschinengewehr (Schwarzlose) M. 7, also known as the Schwarzlose MG, is a medium machine-gun, used as a standard issue firearm in the Austro-Hungarian Army throughout World War I. It was utilized by the Dutch, Greek and Hungarian armies dur ...
etc., that do not lock the breech but instead use some type of delayed blowback.


Design

Most modern machine guns are of the locking type, and of these, most utilize the principle of
gas-operated reloading Gas-operation is a system of operation used to provide energy to operate locked breech, autoloading firearms. In gas-operation, a portion of high-pressure gas from the cartridge being fired is used to power a mechanism to dispose of the spen ...
, which taps off some of the propellant gas from the fired cartridge, using its mechanical pressure to unlock the bolt and cycle the action. The first of these was invented by the French brothers Claire, who patented a gas operated rifle, which included a gas cylinder, in 1892. The Russian
PK machine gun The PK (russian: Пулемёт Калашникова, transliterated as ''Pulemyot Kalashnikova'', or "Kalashnikov's machine gun"), is a belt-fed general-purpose machine gun, chambered for the 7.62×54mmR rimmed cartridge. Designed in the ...
is a more modern example. Another efficient and widely used format is the recoil actuated type, which uses the gun's recoil energy for the same purpose. Machine guns such as the
M2 Browning The M2 machine gun or Browning .50 caliber machine gun (informally, "Ma Deuce") is a heavy machine gun that was designed towards the end of World War I by John Browning. Its design is similar to Browning's earlier M1919 Browning machine gun, ...
and MG42, are of this second kind. A cam, lever or actuator absorbs part of the energy of the recoil to operate the gun mechanism. An externally actuated weapon uses an external power source, such as an electric motor or hand crank, to move its mechanism through the firing sequence. Modern weapons of this type are often referred to as
Gatling gun The Gatling gun is a rapid-firing multiple-barrel firearm invented in 1861 by Richard Jordan Gatling. It is an early machine gun and a forerunner of the modern electric motor-driven rotary cannon. The Gatling gun's operation centered on a c ...
s, after the original inventor (not only of the well-known hand-cranked 19th century proto-machine gun, but also of the first electrically powered version). They have several barrels each with an associated chamber and action on a rotating carousel and a system of cams that load, cock, and fire each mechanism progressively as it rotates through the sequence; essentially each barrel is a separate bolt-action rifle using a common feed source. The continuous nature of the rotary action, and its relative immunity to overheating allow for a very high cyclic
rate of fire Rate of fire is the frequency at which a specific weapon can fire or launch its projectiles. This can be influenced by several factors, including operator training level, mechanical limitations, ammunition availability, and weapon condition. In m ...
, often several thousand rounds per minute. Rotary guns are less prone to jamming than a gun operated by gas or recoil, as the external power source will eject misfired rounds with no further trouble, but this is not possible in the rare cases of self-powered rotary guns. Rotary designs are intrinsically comparatively bulky and expensive, and are therefore generally used with large rounds, 20 mm in diameter or more, often referred to as
Rotary cannon A rotary cannon, rotary autocannon, rotary gun or Gatling cannon, is any large- caliber multiple-barreled automatic firearm that uses a Gatling-type rotating barrel assembly to deliver a sustained saturational direct fire at much greater r ...
– though the rifle-calibre
Minigun The M134 Minigun is an American 7.62×51mm NATO six-barrel rotary machine gun with a high rate of fire (2,000 to 6,000 rounds per minute). It features a Gatling-style rotating barrel assembly with an external power source, normally an electric ...
is an exception to this. Whereas such weapons are highly reliable and formidably effective, one drawback is that the weight and size of the power source and driving mechanism makes them usually impractical for use outside of a vehicle or aircraft mount.
Revolver cannon A revolver cannon is a type of autocannon, commonly used as an aircraft gun. It uses a cylinder with multiple chambers, like those of a revolver handgun, to speed up the loading-firing-ejection cycle. Some examples are also power-driven, to fur ...
s, such as the
Mauser MK 213 The Mauser MG 213 was a 20 mm aircraft-mounted revolver cannon developed for the ''Luftwaffe'' during World War II. It was never put into service, but the principles formed the basis for several post-war developments by the Allies. A 30 mm ve ...
, were developed in World War II by the Germans to provide high-caliber cannons with a reasonable rate of fire and reliability. In contrast to the rotary format, such weapons have a single barrel and a recoil-operated carriage holding a revolving chamber with typically five chambers. As each round is fired, electrically, the carriage moves back rotating the chamber which also ejects the spent case, indexes the next live round to be fired with the barrel and loads the next round into the chamber. The action is very similar to that of the revolver pistols common in the 19th and 20th centuries, giving this type of weapon its name. A
Chain gun A chain gun is a type of autocannon or machine gun that uses an external source of power to cycle the weapon's action, rather than diverting excess energy from the cartridges' propellant as in a typical automatic firearm, and does so via a cont ...
is a specific, patented type of Revolver cannon, the name, in this case, deriving from its driving mechanism. As noted above, firing a machine gun for prolonged periods produces large amounts of heat. In a worst-case scenario, this may cause a cartridge to overheat and detonate even when the trigger is not pulled, potentially leading to damage or causing the gun to cycle its action and keep firing until it has exhausted its ammunition supply or jammed; this is known as ''
cooking off Cooking off (or thermally induced firing) is unfired weapon ammunition exploding prematurely due to heat in the surrounding environment. The term is used both for detonation of ammunition not loaded into a weapon, and unintended firing of a loa ...
'' ( as distinct from ''runaway fire'' where the sear fails to re-engage when the trigger is released). To guard against cook-offs occurring, some kind of cooling system or design element is required. Early machine guns were often
water-cooled Cooling tower and water discharge of a nuclear power plant Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and n ...
and while this technology was very effective, (and was indeed one of the sources of the notorious efficiency of machine guns during the First World War ), the water jackets also added considerable weight to an already bulky design; they were also vulnerable to the enemies' bullets themselves. Armour could be provided, and in WW I the Germans in particular often did this; but this added yet more weight to the guns. Air-cooled machine guns often feature quick-change barrels (often carried by a crew member), passive cooling fins, or in some designs forced-air cooling, such as that employed by the Lewis Gun. Advances in metallurgy and the use of special composites in barrel liners have allowed for greater heat absorption and dissipation during firing. The higher the rate of fire, the more often barrels must be changed and allowed to cool. To minimize this, most air-cooled guns are fired only in short bursts or at a reduced rate of fire. Some designs – such as the many variants of the MG42 – are capable of rates of fire in excess of 1,200 rounds per minute. Motorized Gatling guns are capable of the fastest firing rates of all, partly because this format involves extra energy being injected into the system from outside, instead of depending on energy derived from the propellant contained within the cartridges, partly because the next round can be inserted simultaneously with or before the ejection of the previous cartridge case, and partly because this design intrinsically deals with the unwanted heat very efficiently – effectively quick-changing the barrel and chamber after every shot. The multiple guns that comprise a Gatling being a much larger bulk of metal than other, single-barreled guns, they are thus much slower to rise in temperature for a given amount of heat, while at the same time they are also much better at shedding the excess, as the extra barrels provide a larger surface area from which to dissipate the unwanted thermal energy. In addition to that, they are in the nature of the design spun at very high speed during rapid fire, which has the benefit of producing enhanced air-cooling as a side-effect. In weapons where the round seats and fires at the same time, mechanical timing is essential for operator safety, to prevent the round from firing before it is seated properly. Machine guns are controlled by one or more mechanical sears. When a sear is in place, it effectively stops the bolt at some point in its range of motion. Some sears stop the bolt when it is locked to the rear. Other sears stop the firing pin from going forward after the round is locked into the chamber. Almost all machine guns have a "safety"
sear The Sahar Elevated Access Road, abbreviated to SEAR, is a dedicated, elevated, express access road in Mumbai that connects the Western Express Highway (WEH) near Hanuman Nagar junction in Vile Parle, with the forecourts of Terminal T2 of the C ...
, which simply keeps the trigger from engaging.


History

The first successful machine-gun designs were developed in the mid-19th century. The key characteristic of modern machine guns, their relatively high rate of fire and more importantly mechanical loading, first appeared in the Model 1862
Gatling gun The Gatling gun is a rapid-firing multiple-barrel firearm invented in 1861 by Richard Jordan Gatling. It is an early machine gun and a forerunner of the modern electric motor-driven rotary cannon. The Gatling gun's operation centered on a c ...
, which was adopted by the
United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
. These weapons were still powered by hand; however, this changed with
Hiram Maxim Sir Hiram Stevens Maxim (5 February 1840 – 24 November 1916) was an American- British inventor best known as the creator of the first automatic machine gun, the Maxim gun. Maxim held patents on numerous mechanical devices such as hair-curl ...
's idea of harnessing recoil energy to power reloading in his
Maxim machine gun The Maxim gun is a recoil-operated machine gun invented in 1884 by Hiram Stevens Maxim. It was the first fully automatic machine gun in the world. The Maxim gun has been called "the weapon most associated with imperial conquest" by historian M ...
. Dr. Gatling also experimented with electric-motor-powered models; as discussed above, this externally powered machine reloading has seen use in modern weapons as well. While technical use of the term "machine gun" has varied, the modern definition used by the Sporting Arms and Ammunition Manufacturers' Institute of America is "a fully automatic firearm that loads, fires and ejects continuously when the trigger is held to the rear until the ammunition is exhausted or pressure on the trigger is released." This definition excludes most early manually operated repeating arms the Gatling gun and such as volley guns like the
Nordenfelt gun The Nordenfelt gun was a multiple-barrel organ gun that had a row of up to twelve barrels. It was fired by pulling a lever back and forth and ammunition was gravity fed through chutes for each barrel. It was produced in a number of different ...
.


Medieval

The first known ancestors of multi-shot weapons were medieval organ guns. An early example of an attempt at the mechanisation of one of these would be an 'engine of war' produced in the mid-1570s in England capable of firing from 160 to 320 shots 4, 8, 12 or 24 bullets at a time at a rate of fire up to roughly 3 times the rate of fire of the typical arquebusier of the day. It was also claimed that the gun could be reloaded 'as often as you like' and fired no matter the weather though the English government never adopted the weapon despite testing being carried out at the
Tower of London The Tower of London, officially His Majesty's Royal Palace and Fortress of the Tower of London, is a historic castle on the north bank of the River Thames in central London. It lies within the London Borough of Tower Hamlets, which is sep ...
. The first firearms to have the ability to fire multiple shots from a single barrel without a full manual reload were revolvers made in Europe in the late 1500s. One is a shoulder-gun-length weapon made in Nuremberg, Germany, circa 1580. Another is a revolving
arquebus An arquebus ( ) is a form of long gun that appeared in Europe and the Ottoman Empire during the 15th century. An infantryman armed with an arquebus is called an arquebusier. Although the term ''arquebus'', derived from the Dutch word ''Haakbus ...
, produced by Hans Stopler of Nuremberg in 1597.


17th century

True repeating long arms were difficult to manufacture prior to the development of the unitary firearm cartridge; nevertheless, lever-action repeating rifles such as the
Kalthoff repeater The Kalthoff repeater was a type of repeating firearm that was designed by members of the Kalthoff family around 1630, and became the first repeating firearm to be brought into military service. At least nineteen gunsmiths are known to have mad ...
and
Cookson repeater The Cookson flintlock rifle, a lever-action breech-loading repeater, also known as the Cookson gun, is one of many similar designs to make an appearance on the world stage beginning in the 17th century. The Victoria & Albert Museum in London has ...
were made in small quantities in the 17th century. Perhaps the earliest examples of predecessors to the modern machine gun are to be found in East Asia. According to the Wu-Pei-Chih, a booklet examining Chinese military equipment produced during the first quarter of the 17th century, the Chinese army had in its arsenal the 'Po-Tzu Lien-Chu-P'ao' or 'string-of-100-bullets cannon'. This was a repeating cannon fed by a hopper containing balls which fired its charges sequentially. The way it worked was similar to the Perkins steam gun of 1824 or the Beningfield electrolysis gun of 1845 only slow-burning gunpowder was used as the propelling force in place of steam or the gases produced by electrolysis. Another repeating gun was produced by a Chinese commoner, Dai Zi, in the late 17th century. This weapon was also hopper-fed and never went into mass production. In 1655, a way of loading, aiming and shooting up to 6 wall muskets 60 times in a minute for a total rate of fire of 360 shots per minute was mentioned in ''The Century of Inventions'' by
Edward Somerset, 2nd Marquess of Worcester Edward Somerset, 2nd Marquess of Worcester (9 March 1602 or 9 March 16033 April 1667), styled Lord Herbert of Raglan from 1628 to 1644, was an English nobleman involved in royalist politics, and an inventor. While Earl of Glamorgan, he was se ...
, though, like all the inventions mentioned in the book, it is uncertain if it was ever built. It is sometimes claimed (i.e. in George Morgan Chinn's ''the Machine Gun'') that in 1663 the first mention of the automatic principle of machine guns was in a paper presented to the Royal Society of England by Palmer, an Englishman who described a volley gun capable of being operated by either recoil or gas. However, no one has been able to find this paper in recent times and all references to a multi-shot weapon by a Palmer during this period appear to be referring to a somewhat more common
Kalthoff repeater The Kalthoff repeater was a type of repeating firearm that was designed by members of the Kalthoff family around 1630, and became the first repeating firearm to be brought into military service. At least nineteen gunsmiths are known to have mad ...
or Lorenzoni-system gun. Despite this, there is a reference in 1663 to at least the concept of a genuine automatic gun that was presented to
Prince Rupert Prince Rupert of the Rhine, Duke of Cumberland, (17 December 1619 (O.S.) / 27 December (N.S.) – 29 November 1682 (O.S.)) was an English army officer, admiral, scientist and colonial governor. He first came to prominence as a Royalist caval ...
, though its type and method of operation are unknown.


18th century

In 1708 it was reported from Constantinople that a French officer had invented a very light cannon that could fire from a single barrel 30 shots in 2 and a half minutes for a total rate of fire of 12 shots a minute. In 1711 a French lawyer presented to the parliament of Dijon a 'war machine' made up of 10 carbine barrels capable of firing continuously. Another early revolving gun was created by
James Puckle James Puckle (1667–1724) was an English inventor, lawyer and writer from London chiefly remembered for his invention of the ''Defence Gun'', better known as the '' Puckle gun'', a multi-shot gun mounted on a stand capable of (depending on whi ...
, a London lawyer, who patented what he called "The Puckle Gun" on May 15, 1718. It was a design for a manually operated 1.25 in. (32 mm) caliber,
flintlock Flintlock is a general term for any firearm that uses a flint-striking ignition mechanism, the first of which appeared in Western Europe in the early 16th century. The term may also apply to a particular form of the mechanism itself, also know ...
cannon with a revolver cylinder able to fire 6–11 rounds before reloading by swapping out the cylinder, intended for use on
ship A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished ...
s.Original patent claim reproduced in: Francis Bannerman Sons, ''Bannerman Military Goods Catalogue #28'' (1954) p. 103 It was one of the earliest weapons to be referred to as a machine gun, being called such in 1722, though its operation does not match the modern usage of the term. According to Puckle, it was able to fire round bullets at
Christians Christians () are people who follow or adhere to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus Christ. The words ''Christ'' and ''Christian'' derive from the Koine Greek title ''Christós'' (Χρ� ...
and square bullets at
Turks Turk or Turks may refer to: Communities and ethnic groups * Turkic peoples, a collection of ethnic groups who speak Turkic languages * Turkish people, or the Turks, a Turkic ethnic group and nation * Turkish citizen, a citizen of the Republic ...
. However, it was a commercial failure and was not adopted or produced in any meaningful quantity. In 1720 a French inventor called Philippe Vayringe invented a small cannon that could fire 16 shots in succession which he demonstrated before the Duke of Lorraine. In 1737, it was mentioned that Jacob de Weinholtz, a Dane who was serving in the Portuguese army, had invented a cannon capable of firing 20 to 30 shots a minute though requiring 15 people to work it. The cannons were brought along with a Portuguese fleet sent to India to take part in a colonial war in the 1740s. Also in 1737 it was mentioned that a German engineer had invented a 10-pounder cannon capable of firing 20 times in a minute. In 1740, a cannon able to shoot 11 times per minute was developed by a Frenchman called Chevalier de Benac. Meanwhile, not long after in England, in 1747 a cannon able to simultaneously charge and discharge itself 20 times in a minute was invented by James Allis and presented to the Royal Society of England. In 1750, in Denmark a Prussian known as Captain Steuben of the Train of Artillery invented a breech-loading cannon worked by 4 people and fed by paper cartridges capable of firing 24 times in a minute and demonstrated it to the King of Denmark along with some other high-ranking officials in the same year. In 1764, Frenchman Ange Goudar wrote in his work ''The Chinese Spy'' that he had assisted in Paris in the proofing of a 'great gun' capable of firing 60 times in a minute. In 1773, another cannon capable of firing 23 or 24 times in a minute and cleaning itself after every shot was invented by
Thomas Desaguliers Lieutenant-General Thomas Desaguliers (5 January 1721 – 1 March 1780) was a British Army general and a Colonel Commandant of the Royal Artillery. Biography Desaguliers was born 5 January 1721, the youngest son of Dr. John Theophilus Desagul ...
. In 1775, it was mentioned that in England two large cannons invented by an unidentified matross at Woolwich had achieved a rate of fire of 59 shots in 59 and a half seconds. Also in 1775, a breech-loading
volley gun A volley gun is a gun with multiple single-shot barrels that shoot projectiles in volley fire, either simultaneously or in succession. Although capable of unleashing intense firepower, volley guns differ from modern machine guns in that the ...
, similar to the later mitrailleuse, was invented by a Frenchman called Du Perron which was worked by 3 or 4 men and capable of discharging 24 barrels 10 times a minute for a total rate of fire of 240 shots per minute. In 1776, a gun capable of charging and discharging itself 120 times 'by the motion of one hand only' in a minute was invented in England by an inventor from the county of Westmoreland. In 1777,
Philadelphia Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Since ...
gunsmith A gunsmith is a person who repairs, modifies, designs, or builds guns. The occupation differs from an armorer, who usually replaces only worn parts in standard firearms. Gunsmiths do modifications and changes to a firearm that may require a very ...
Joseph Belton offered the
Continental Congress The Continental Congress was a series of legislative bodies, with some executive function, for thirteen of Britain's colonies in North America, and the newly declared United States just before, during, and after the American Revolutionary War. ...
a "new improved gun", which was capable of firing up to twenty shots in five seconds; unlike older repeaters using complex lever-action mechanisms, it used a simpler system of
superposed load A superposed load or stacked charge or superimposed load is a method used by various muzzle-loading firearms, from matchlocks to caplocks, as well as newer Metal Storm Limited, Metal Storm weapons, to fire multiple shots from a single barrel witho ...
s, and was loaded with a single large
paper cartridge A paper cartridge is one of various types of small arms ammunition used before the advent of the metallic cartridge. These cartridges consisted of a paper cylinder or cone containing the bullet, gunpowder, and in some cases, a primer or a lub ...
. Congress requested that Belton modify 100 flintlock muskets to fire eight shots in this manner, but rescinded the order when Belton's price proved too high. In 1779 a machine made up of 21 musket barrels worked by 3 men was produced by a British inventor called William Wilson Wright which he claimed could be fired 3 times quicker than a single man could load and fire a musket 3 times. In 1788 a Swiss soldier invented a machine worked by 10 men capable of discharging 300 balls in 3 minutes. Also in 1788 it was reported that a Prussian officer had invented a gun capable of firing 400 balls one after the other. In 1790, a former officer in the French military known as Joseph-François-Louis Grobert invented a 'ballistic machine' or 'pyroballistic machine' with multiple barrels operated by 4 men and a continuous rotational movement capable of firing 360 rifle shots a minute in a variety of calibers. In 1792, a French artist known as Renard invented a piece of ordnance that could be operated by one man and fired 90 shots a minute. Also in 1792 a French mechanic called Garnier invented a musket battery made up of 15 barrels capable of firing 300 shots in 2 minutes for a total rate of fire of 150 shots a minute or 10 shots per minute per barrel and of being operated by one man.


19th century

In the early and mid-19th century, a number of rapid-firing weapons appeared which offered multi-shot fire, mostly
volley gun A volley gun is a gun with multiple single-shot barrels that shoot projectiles in volley fire, either simultaneously or in succession. Although capable of unleashing intense firepower, volley guns differ from modern machine guns in that the ...
s. Volley guns (such as the Mitrailleuse) and double-barreled pistols relied on duplicating all parts of the gun, though the
Nock gun The Nock gun was a seven-barrelled flintlock smoothbore firearm used by the Royal Navy during the early stages of the Napoleonic Wars. It is a type of volley gun adapted for ship-to-ship fighting, but was limited in its use because of the powerful ...
used the otherwise-undesirable "chain fire" phenomenon (where multiple chambers are ignited at once) to propagate a spark from a single flintlock mechanism to multiple barrels. Pepperbox pistols also did away with needing multiple hammers but used multiple manually operated barrels. Revolvers further reduced this to only needing a pre-prepared cylinder and linked advancing the cylinder to cocking the hammer. However, these were still manually operated. In 1805 a British inventor from Northampton designed a cannon that would prime, load and fire itself 10 times a minute. In 1806 a Viennese copper engraver and mechanic known as Mr Putz invented a machine cannon that could load, fire and clean itself once every second or potentially up to 60 times a minute though the rate of fire was limited by the overheating of the barrel. In 1819 an American inventor from Baltimore designed a gun with 11 barrels that could fire 12 times in a minute for a total rate of fire of 132 shots a minute. In 1821, a muzzle-loading repeating cannon capable of firing 30 shots in 6 minutes or 5 shots per minute was demonstrated in England by the French-American "Fire King" Ivan Ivanitz Chabert. It was worked by a "wheel" fed by paper cartridges from a store attached to the cannon and ignited using a match from a match-holder somewhere else on the cannon. In 1828, a
swivel gun The term swivel gun (or simply swivel) usually refers to a small cannon, mounted on a swiveling stand or fork which allows a very wide arc of movement. Another type of firearm referred to as a swivel gun was an early flintlock combination gun wi ...
that did not need cleaning or muzzle-loading and was capable of being made to any dimensions and used as an ordinary cannon at a moment's notice and firing 40 shots a minute was invented by a native of Ireland. In France, in 1831, a mechanic from the Vosges department invented a lever-operated cannon that could fire 100 shots a minute. In 1832, a machine capable of firing 500 rifle shots a minute was devised by Hamel, a French mechanic. In the mid-1830s, a machine gun was designed by John Steuble (
Swiss Swiss may refer to: * the adjectival form of Switzerland *Swiss people Places * Swiss, Missouri *Swiss, North Carolina * Swiss, West Virginia *Swiss, Wisconsin Other uses * Swiss-system tournament, in various games and sports * Swiss Internation ...
), who tried to sell it to the Russian, English and French governments. The English and Russian governments showed interest but the former refused to pay Steuble, who later sued them for this transgression, and the latter tried to imprison him. The French government showed interest at first and while it noted that mechanically there was nothing wrong with Steuble's invention it turned him down, stating that the machine both lacked novelty and could not be usefully employed by the army. The gun was reportedly breech-loading, fed by cartridges from some kind of hopper and could fire 34 barrels of one-inch calibre 4 or 6 times for a total of 136 or 204 shots a minute. A biography of
William Lyon Mackenzie William Lyon Mackenzie (March12, 1795 August28, 1861) was a Scottish Canadian-American journalist and politician. He founded newspapers critical of the Family Compact, a term used to identify elite members of Upper Canada. He represented Yor ...
mentions that in 1839 a Detroit-based inventor was working on a cannon that could be fired 50 to 60 times in a minute. In 1842, Dr. Thomson or Thompson, an American, invented a cannon fed by pre-loaded breech-pieces with 4 barrels that was operated by means of a revolving cylinder and could be fired 50 times in as many seconds or even up to 500 times in 500 seconds. In 1846, Mr. Francis Dixon, an American, invented a cannon that loaded, primed and discharged itself through the use of a brake at a rate of fire of 30 to 40 shots a minute. A variation of it was worked by clockwork-like machinery and could be made to move by itself a certain distance along rails before firing 10 times and returning to its original position. Also in 1846, in Canada, inventor Simeon "Larochelle" Gautron, invented a cannon that was similar to a wooden model of a repeating cannon he constructed in 1836 but for which he had made a number of improvements since then which could be fired 10 or 12 times in a minute when the typical muzzle-loading cannon of the day could be fired at only a fraction of that speed, and an English newspaper reporting on it claimed it could be fired up to 60 times in the same period of time, and clean itself after every shot. It was worked by a crank, could be worked by one man when the typical cannon of the day required twelve or more, was fed by paper cartridges from a revolving cylinder and used separate percussion caps for ignition. Larochelle tried to interest the Canadian military in his invention but was turned down for reasons of complexity and expense which, while it drew some criticism from the French language Canadian press, led to the inventor discontinuing development of it in favour of more profitable activities. A model of Larochelle's cannon is still on display at the Musee National des Beaux-Arts du Quebec. In 1847, a short description of a prototype electrically ignited mechanical machine gun was published in Scientific American by J.R. Nichols. The model described is small in scale and works by rotating a series of barrels vertically so that it is feeding at the top from a "tube" or hopper and could be discharged immediately at any elevation after having received a charge, according to the author. In 1848, the Italian Cesare Rosaglio announced his invention of a machine gun capable of being operated by a single man and firing 300 rifle shots a minute or 12,000 in an hour after taking into account the time needed to reload the "tanks" of ammunition. In June 1851, a model of a 'war engine' allegedly capable of firing 10,000 ball cartridges in 10 minutes was demonstrated by a British inventor called Francis McGetrick. In 1852, a
rotary cannon A rotary cannon, rotary autocannon, rotary gun or Gatling cannon, is any large- caliber multiple-barreled automatic firearm that uses a Gatling-type rotating barrel assembly to deliver a sustained saturational direct fire at much greater r ...
using a unique form of wheellock ignition was demonstrated by Delany, an Irish immigrant to America. In 1854, a British patent for a mechanically operated machine gun was filed by Henry Clarke. This weapon used multiple barrels arranged side by side, fed by a revolving cylinder that was in turn fed by hoppers, similar to the system used by Nichols. The gun could be fired by percussion or electricity, according to the author. Unlike other mechanically operated machine guns of the era, this weapon did not use any form of self-contained cartridge, with firing being carried out by separate percussion caps. In the same year, water cooling was proposed for machine guns by
Henry Bessemer Sir Henry Bessemer (19 January 1813 – 15 March 1898) was an English inventor, whose steel-making process would become the most important technique for making steel in the nineteenth century for almost one hundred years from 1856 to 1950. He ...
, along with a water cleaning system, though he later abandoned this design. In his patent, Bessemer describes a hydropneumatic delayed-blowback-operated, fully automatic cannon. Part of the patent also refers to a steam-operated piston to be used with firearms but the bulk of the patent is spent detailing the former system. In America, a patent for a machine gun-type weapon was filed by John Andrus Reynolds in 1855. Another early American patent for a manually operated machine gun with a blowback-operated cocking mechanism was filed by C. E. Barnes in 1856. In France and Britain, a mechanically operated machine gun was patented in 1856 by Frenchman Francois Julien. This weapon was a cannon that fed from a type of open-ended tubular magazine, only using rollers and an endless chain in place of springs. The
Agar Gun The Agar gun (or Ager) was an early rapid fire machine gun developed during the US Civil War. The weapon was nicknamed the Coffee Mill Gun, and was also called the Union Repeating Gun. History During the Civil War, inventors were encouraged to ...
, otherwise known as a "coffee-mill gun" because of its resemblance to a coffee mill, was invented by Wilson Agar at the beginning of the US Civil War. The weapon featured mechanized loading using a hand crank linked to a hopper above the weapon. The weapon featured a single barrel and fired through the turning of the same crank; it operated using paper cartridges fitted with percussion caps and inserted into metal tubes that acted as chambers; it was therefore functionally similar to a revolver. The weapon was demonstrated to President Lincoln in 1861. He was so impressed with the weapon that he purchased 10 on the spot for $1,500 apiece. The Union Army eventually purchased a total of 54 of the weapons. However, due to antiquated views of the Ordnance Department the weapons, like its more famous counterpart the Gatling Gun, saw only limited use. The
Gatling gun The Gatling gun is a rapid-firing multiple-barrel firearm invented in 1861 by Richard Jordan Gatling. It is an early machine gun and a forerunner of the modern electric motor-driven rotary cannon. The Gatling gun's operation centered on a c ...
, patented in 1861 by Richard Jordan Gatling, was the first to offer controlled, sequential fire with mechanical loading. The design's key features were machine loading of prepared cartridges and a hand-operated crank for sequential high-speed firing. It first saw very limited action in the
American Civil War The American Civil War (April 12, 1861 – May 26, 1865; also known by Names of the American Civil War, other names) was a civil war in the United States. It was fought between the Union (American Civil War), Union ("the North") and t ...
; it was subsequently improved and used in the Franco-Prussian war and
North-West Rebellion The North-West Rebellion (french: Rébellion du Nord-Ouest), also known as the North-West Resistance, was a Resistance movement, resistance by the Métis people (Canada), Métis people under Louis Riel and an associated uprising by First Natio ...
. Many were sold to other armies in the late 19th century and continued to be used into the early 20th century until they were gradually supplanted by Maxim guns. Early multi-barrel guns were approximately the size and weight of contemporary
artillery Artillery is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during si ...
pieces, and were often perceived as a replacement for cannon firing
grapeshot Grapeshot is a type of artillery round invented by a British Officer during the Napoleonic Wars. It was used mainly as an anti infantry round, but had other uses in naval combat. In artillery, a grapeshot is a type of ammunition that consists of ...
or
canister shot Canister shot is a kind of anti-personnel artillery ammunition. Canister shot has been used since the advent of gunpowder-firing artillery in Western armies. However, canister shot saw particularly frequent use on land and at sea in the various ...
.Emmott, N.W. "The Devil's Watering Pot" ''United States Naval Institute Proceedings'' September 1972 p. 70 The large wheels required to move these guns around required a high firing position, which increased the vulnerability of their crews. Sustained firing of
gunpowder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). T ...
cartridges generated a cloud of smoke, making concealment impossible until
smokeless powder Finnish smokeless powderSmokeless powder is a type of propellant used in firearms and artillery that produces less smoke and less fouling when fired compared to gunpowder ("black powder"). The combustion products are mainly gaseous, compared t ...
became available in the late 19th century.Emmott, N.W. "The Devil's Watering Pot" ''United States Naval Institute Proceedings'' September 1972 p. 72 Gatling guns were targeted by artillery they could not reach, and their crews were targeted by
sniper A sniper is a military/paramilitary marksman who engages targets from positions of concealment or at distances exceeding the target's detection capabilities. Snipers generally have specialized training and are equipped with high-precision r ...
s they could not see. The Gatling gun was used most successfully to expand European colonial empires, since against poorly equipped indigenous armies it did not face such threats. In 1864, in the aftermath of the
Second Schleswig War The Second Schleswig War ( da, Krigen i 1864; german: Deutsch-Dänischer Krieg) also sometimes known as the Dano-Prussian War or Prusso-Danish War was the second military conflict over the Schleswig-Holstein Question of the nineteenth century. T ...
, Denmark started a program intended to develop a gun that used the recoil of a fired shot to reload the firearm though a working model would not be produced until 1888. In 1870, a Lt. Holsten Friberg of the Swedish army patented a fully automatic recoil-operated firearm action and may have produced firing prototypes of a derived design around 1882: this was the forerunner to the 1907
Kjellman machine gun The Kjellman LMG was a machine gun produced in Sweden. It is notable for being one of the first fully automatic weapons ever conceived (if not produced) and one of the first light machine guns as well. Although the patent dated back to 1870, and ...
, though, due to rapid residue buildup from the use of black powder, Friberg's design was not a practical weapon. Also in 1870, the Bavarian regiment of the Prussian army used a unique mitrailleuse-style weapon in the Franco-Prussian war. The weapon was made up of four barrels placed side by side that replaced the manual loading of the French mitrailleuse with a mechanical loading system featuring a hopper containing 41 cartridges at the breech of each barrel. Although it was used effectively at times, mechanical difficulties hindered its operation and it was ultimately abandoned shortly after the war ended ( de).


Maxim and World War I

The first practical self-powered machine gun was invented in 1884 by Sir Hiram Maxim. The
Maxim machine gun The Maxim gun is a recoil-operated machine gun invented in 1884 by Hiram Stevens Maxim. It was the first fully automatic machine gun in the world. The Maxim gun has been called "the weapon most associated with imperial conquest" by historian M ...
used the recoil power of the previously fired bullet to reload rather than being hand-powered, enabling a much higher rate of fire than was possible using earlier designs such as the
Nordenfelt The Nordenfelt gun was a multiple-barrel organ gun that had a row of up to twelve barrels. It was fired by pulling a lever back and forth and ammunition was gravity fed through chutes for each barrel. It was produced in a number of different c ...
and Gatling weapons. Maxim also introduced the use of water cooling, via a water jacket around the barrel, to reduce overheating. Maxim's gun was widely adopted, and derivative designs were used on all sides during the First World War. The design required fewer crew and was lighter and more usable than the Nordenfelt and Gatling guns. First World War combat experience demonstrated the military importance of the machine gun. The United States Army issued four machine guns per regiment in 1912, but that allowance increased to 336 machine guns per regiment by 1919. Heavy guns based on the Maxim such as the
Vickers machine gun The Vickers machine gun or Vickers gun is a water-cooled .303 British (7.7 mm) machine gun produced by Vickers Limited, originally for the British Army. The gun was operated by a three-man crew but typically required more men to move and o ...
were joined by many other machine weapons, which mostly had their start in the early 20th century such as the
Hotchkiss machine gun The Hotchkiss machine gun was any of a line of products developed and sold by Hotchkiss et Cie, (full name Société Anonyme des Anciens Etablissements Hotchkiss et Cie), established by United States gunsmith Benjamin B. Hotchkiss. Hotchkiss moved ...
.
Submachine gun A submachine gun (SMG) is a magazine-fed, automatic carbine designed to fire handgun cartridges. The term "submachine gun" was coined by John T. Thompson, the inventor of the Thompson submachine gun, to describe its design concept as an autom ...
s (e.g., the German
MP 18 The MP 18, manufactured by Theodor Bergmann ''Abteilung Waffenbau'', was arguably the first submachine gun used in combat. It was introduced into service in 1918 by the German Army during World War I as the primary weapon of the ''Sturmtruppen' ...
) as well as lighter machine guns (the first light machine gun deployed in any significant number being the
Madsen machine gun The Madsen is a light machine gun that Julius A. Rasmussen and Theodor Schouboe designed and proposed for adoption by Colonel Vilhelm Herman Oluf Madsen, the Danish Minister of War, and that the Royal Danish Army adopted in 1902. It was the wo ...
, with the
Chauchat The Chauchat ("show-sha", ) was the standard light machine gun or "machine rifle" of the French Army during World War I (1914–18). Its official designation was "Fusil Mitrailleur Modele 1915 CSRG" ("Machine Rifle Model 1915 CSRG"). Beginning i ...
and Lewis gun soon following) saw their first major use in
World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...
, along with heavy use of large-caliber machine guns. The biggest single cause of
casualties A casualty, as a term in military usage, is a person in military service, combatant or non-combatant, who becomes unavailable for duty due to any of several circumstances, including death, injury, illness, capture or desertion. In civilian usag ...
in World War I was actually artillery, but combined with wire entanglements, machine guns earned a fearsome reputation. Another fundamental development occurring before and during the war was the incorporation by gun designers of machine gun auto-loading mechanisms into handguns, giving rise to semi-automatic pistols such as the Borchardt (1890s), automatic
machine pistol A machine pistol is an autoloading pistol capable of fully automatic fire. The term can also be used to describe a stockless handgun-style submachine gun. The term is a calque of ''Maschinenpistole'', the German word for submachine guns. Ma ...
s and later submachine guns (such as the
Beretta 1918 The Moschetto Automatico Revelli-Beretta Mod. 1915 (Commonly known as the Beretta Model 1918) was a self-loading carbine that entered service in 1918 with the Italian armed forces. Designed as a semi-automatic rifle, the weapon came with an over ...
). Aircraft-mounted machine guns were first used in combat in
World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...
. Immediately this raised a fundamental problem. The most effective position for guns in a single-seater fighter was clearly, for the purpose of aiming, directly in front of the pilot; but this placement would obviously result in bullets striking the moving propeller. Early solutions, aside from simply hoping that luck was on the pilot's side with an unsynchronized forward-firing gun, involved either aircraft with pusher props like the
Vickers F.B.5 The Vickers F.B.5 (Fighting Biplane 5) (known as the "Gunbus") was a British two-seat pusher military biplane of the First World War. Armed with a single .303 in (7.7 mm) Lewis gun operated by the observer in the front of the ...
, Royal Aircraft Factory F.E.2 and Airco DH.2, wing mounts like that of the
Nieuport 10 The Nieuport 10 (or Nieuport XB in contemporary sources) was a French First World War sesquiplane that filled a wide variety of roles, including reconnaissance, fighter and trainer. Design and development In January 1914, designer Gustave Delag ...
and
Nieuport 11 The Nieuport 11 (or Nieuport XI C.1 in contemporary sources), nicknamed the ''Bébé'', was a French World War I single seat sesquiplane fighter aircraft, designed by Gustave Delage. It was the primary aircraft that ended the Fokker Scourge in ...
which avoided the propeller entirely, or armored propeller blades such as those mounted on the
Morane-Saulnier L The Morane-Saulnier L, or Morane-Saulnier Type L, or officially MoS-3, was a French parasol wing one or two-seat scout aeroplane of the First World War. The Type L became one of the first successful fighter aircraft when it was fitted with a si ...
which would allow the propeller to deflect unsynchronized gunfire. By mid 1915, the introduction of a reliable gun synchronizer by the
Imperial German Flying Corps Imperial is that which relates to an empire, emperor, or imperialism. Imperial or The Imperial may also refer to: Places United States * Imperial, California * Imperial, Missouri * Imperial, Nebraska * Imperial, Pennsylvania * Imperial, Texas ...
made it possible to fire a closed-bolt machine gun forward through a spinning propeller by timing the firing of the gun to miss the blades. The Allies had no equivalent system until 1916 and their aircraft suffered badly as a result, a period known as the Fokker Scourge, after the
Fokker Eindecker The Fokker ''Eindecker'' fighters were a series of German World War I monoplane single-seat fighter aircraft designed by Dutch engineer Anthony Fokker.Boyne 1988 Developed in April 1915, the first ''Eindecker'' ("Monoplane") was the first purpose ...
, the first German plane to incorporate the new technology.


Interwar era and World War II

As better materials became available following the First World War, light machine guns became more readily portable; designs such as the
Bren light machine gun The Bren gun was a series of light machine guns (LMG) made by Britain in the 1930s and used in various roles until 1992. While best known for its role as the British and Commonwealth forces' primary infantry LMG in World War II, it was also used ...
replaced bulky predecessors like the Lewis gun in the squad support weapon role, while the modern division between medium machine guns like the
M1919 Browning machine gun The M1919 Browning is a .30 caliber medium machine gun that was widely used during the 20th century, especially during World War II, the Korean War, and the Vietnam War. The M1919 saw service as a light infantry, coaxial, mounted, aircraft, ...
and heavy machine guns like the
Browning M2 The M2 machine gun or Browning .50 caliber machine gun (informally, "Ma Deuce") is a heavy machine gun that was designed towards the end of World War I by John Browning. Its design is similar to Browning's earlier M1919 Browning machine gun, ...
became clearer. New designs largely abandoned water jacket cooling systems as both undesirable, due to a greater emphasis on mobile tactics; and unnecessary, thanks to the alternative and superior technique of preventing overheating by swapping barrels. The interwar years also produced the first widely used and successful
general-purpose machine gun A general-purpose machine gun (GPMG) is an air-cooled, usually belt-fed machine gun that can be adapted flexibly to various tactical roles for light and medium machine guns. A GPMG typically features a quick-change barrel design calibered for v ...
, the German
MG 34 The MG 34 (shortened from German: ''Maschinengewehr 34'', or "machine gun 34") is a German recoil-operated air-cooled general-purpose machine gun, first tested in 1929, introduced in 1934, and issued to units in 1936. It introduced an entirely n ...
. While this machine gun was equally able in the light and medium roles, it proved difficult to manufacture in quantity, and experts on industrial metalworking were called in to redesign the weapon for modern tooling, creating the
MG 42 The MG 42 (shortened from German: ''Maschinengewehr 42'', or "machine gun 42") is a German recoil-operated air-cooled general-purpose machine gun used extensively by the Wehrmacht and the Waffen-SS during the second half of World War II. Enter ...
. This weapon was simpler, cheaper to produce, fired faster, and replaced the MG 34 in every application except vehicle mounts since the MG 42's barrel changing system could not be operated when it was mounted.


Cold War

Experience with the MG42 led to the US issuing a requirement to replace the aging Browning Automatic Rifle with a similar weapon, which would also replace the M1919; simply using the MG42 itself was not possible, as the design brief required a weapon which could be fired from the hip or shoulder like the BAR. The resulting design, the
M60 machine gun The M60, officially the Machine Gun, Caliber 7.62 mm, M60, is a family of American general-purpose machine guns firing 7.62×51mm NATO cartridges from a disintegrating belt of M13 links. There are several types of ammunition approved fo ...
, was issued to troops during the
Vietnam War The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
. As it became clear that a high-volume-of-fire weapon would be needed for fast-moving jet aircraft to reliably hit their opponents, Gatling's work with electrically powered weapons was recalled and the 20 mm
M61 Vulcan The M61 Vulcan is a hydraulically, electrically, or pneumatically driven, six- barrel, air-cooled, electrically fired Gatling-style rotary cannon which fires rounds at an extremely high rate (typically 6,000 rounds per minute). The M61 and i ...
designed; a miniaturized 7.62 mm version initially known as the "mini-Vulcan" and quickly shortened to "
minigun The M134 Minigun is an American 7.62×51mm NATO six-barrel rotary machine gun with a high rate of fire (2,000 to 6,000 rounds per minute). It features a Gatling-style rotating barrel assembly with an external power source, normally an electric ...
" was soon in production for use on helicopters, where the volume of fire could compensate for the instability of the helicopter as a firing platform.


Human interface

The most common interface on machine guns is a
pistol grip On a firearm or other tools, a pistol grip is a distinctly protruded handle underneath the main mechanism, to be held by the user's hand at a more vertical (and thus more ergonomic) angle, similar to the how one would hold a conventional pis ...
and trigger. On earlier manual machine guns, the most common type was a
hand crank A crank is an arm attached at a right angle to a rotating shaft by which circular motion is imparted to or received from the shaft. When combined with a connecting rod, it can be used to convert circular motion into reciprocating motion, or vic ...
. On externally powered machine guns, such as miniguns, an electronic button or trigger on a joystick is commonly used. Light machine guns often have a buttstock attached, while vehicle and
tripod A tripod is a portable three-legged frame or stand, used as a platform for supporting the weight and maintaining the stability of some other object. The three-legged (triangular stance) design provides good stability against gravitational loads ...
mounted machine guns usually have spade grips. In the late 20th century, scopes and other complex optics became more common as opposed to the more basic
iron sights Iron sights are a system of physical alignment markers (usually made of metallic material) used as a sighting device to assist the accurate aiming of ranged weapons (such as a firearm, airgun, crossbow or even compound bow), or less commonly ...
. Loading systems in early manual machine guns were often from a hopper of loose (un-linked) cartridges. Manual-operated volley guns usually had to be reloaded manually all at once (each barrel reloaded by hand, or with a set of cartridges affixed to a plate that was inserted into the weapon). With hoppers, the rounds could often be added while the weapon was firing. This gradually changed to belt-fed types. Belts were either held in the open by the person, or in a bag or box. Some modern vehicle machine guns used linkless feed systems, however. Modern machine guns are commonly mounted in one of four ways. The first is a
bipod A bipod is a V-shaped portable attachment that helps support and steady a device, usually a weapon such as a long gun or a mortar. The term comes from the Latin prefix ''bi-'' and Greek root ''pod'', meaning "two" and "foot" respectively. Bip ...
– often these are integrated with the weapon. This is common on
light machine guns A light machine gun (LMG) is a light-weight machine gun designed to be operated by a single infantryman, with or without an assistant, as an infantry support weapon. LMGs firing cartridges of the same caliber as the other riflemen of the sam ...
and some medium machine guns. Another is a
tripod A tripod is a portable three-legged frame or stand, used as a platform for supporting the weight and maintaining the stability of some other object. The three-legged (triangular stance) design provides good stability against gravitational loads ...
, where the person holding it does not form a "leg" of support. Medium and
heavy machine gun A heavy machine gun (HMG) is significantly larger than light, medium or general-purpose machine guns. HMGs are typically too heavy to be man-portable (carried by one person) and require mounting onto a weapons platform to be operably stable or ...
s usually use tripods. On ships, vehicles, and aircraft, machine guns are usually mounted on a pintle mount – basically, a steel post that is connected to the frame or body. Tripod and pintle mounts are usually used with spade grips. The last major mounting type is one that is disconnected from humans, as part of an armament system, such as a tank coaxial or part of an aircraft's armament. These are usually electrically fired and have complex sighting systems, for example, the
US Helicopter Armament Subsystems The United States military has developed a number of Helicopter Armament Subsystems since the early 1960s. These systems are used for offensive and defensive purposes and make use of a wide variety of weapon types including, but not limited to ma ...
.


See also

* Assault rifle *
Autocannon An autocannon, automatic cannon or machine cannon is a fully automatic gun that is capable of rapid-firing large-caliber ( or more) armour-piercing, explosive or incendiary shells, as opposed to the smaller-caliber kinetic projectiles (bul ...
*
Automatic rifle An automatic rifle is a type of autoloading rifle that is capable of fully automatic fire. Automatic rifles are generally select-fire weapons capable of firing in semi-automatic and automatic firing modes (some automatic rifles are capable of ...
* Breda (machine gun) *
Chain gun A chain gun is a type of autocannon or machine gun that uses an external source of power to cycle the weapon's action, rather than diverting excess energy from the cartridges' propellant as in a typical automatic firearm, and does so via a cont ...
*
Crew-served weapon A crew-served weapon is any weapon system that is issued to a crew of two or more individuals performing the same or separate tasks to run at maximum operational efficiency, as opposed to an individual-service weapon, which only requires one pe ...
*
Firearm action In firearms terminology, an action is the functional mechanism of a breech-loading firearm that handles (loads, locks, fires, extracts and ejects) the ammunition cartridges, or the method by which that mechanism works. Actions are technically n ...
*
Gatling gun The Gatling gun is a rapid-firing multiple-barrel firearm invented in 1861 by Richard Jordan Gatling. It is an early machine gun and a forerunner of the modern electric motor-driven rotary cannon. The Gatling gun's operation centered on a c ...
*
General-purpose machine gun A general-purpose machine gun (GPMG) is an air-cooled, usually belt-fed machine gun that can be adapted flexibly to various tactical roles for light and medium machine guns. A GPMG typically features a quick-change barrel design calibered for v ...
*
Heavy machine gun A heavy machine gun (HMG) is significantly larger than light, medium or general-purpose machine guns. HMGs are typically too heavy to be man-portable (carried by one person) and require mounting onto a weapons platform to be operably stable or ...
*
Light machine gun A light machine gun (LMG) is a light-weight machine gun designed to be operated by a single infantryman, with or without an assistant, as an infantry support weapon. LMGs firing cartridges of the same caliber as the other riflemen of the ...
*
List of firearms This is an extensive list of small arms—including pistols, revolvers, submachine guns, shotguns, battle rifles, assault rifles, sniper rifles, machine guns, personal defense weapons, carbines, designated marksman rifles, flamethrowers, multipl ...
*
List of machine guns This is a list of machine guns and their variants. The tables are sortable. See also *List of firearms *List of multiple-barrel firearms References {{Reflist * Machine guns A machine gun is a fully automatic, rifled autoloading f ...
* List of multiple barrel machine guns *
Medium machine gun A medium machine gun (MMG), in modern terms, usually refers to a belt-fed machine gun firing a full-powered rifle cartridge, and is considered "medium" in weight (). Medium machine guns are light enough to be infantry-portable (as opposed to a h ...
*
Minigun The M134 Minigun is an American 7.62×51mm NATO six-barrel rotary machine gun with a high rate of fire (2,000 to 6,000 rounds per minute). It features a Gatling-style rotating barrel assembly with an external power source, normally an electric ...
* Mitrailleuse *
Personal defense weapon Personal defense weapons (PDWs) are a class of firearms intended for self-defense and security rather than warfare and infantry. Most PDWs fire a small-caliber (less than ), centerfire bottleneck cartridge resembling a scaled-down intermedia ...
*
Revolver cannon A revolver cannon is a type of autocannon, commonly used as an aircraft gun. It uses a cylinder with multiple chambers, like those of a revolver handgun, to speed up the loading-firing-ejection cycle. Some examples are also power-driven, to fur ...
*
Squad automatic weapon A squad automatic weapon (SAW), also known as a section automatic weapon or light support weapon (LSW), is a man-portable automatic firearm attached to infantry squads or sections as a source of rapid direct firepower. Weapons fulfilling t ...
*
Submachine gun A submachine gun (SMG) is a magazine-fed, automatic carbine designed to fire handgun cartridges. The term "submachine gun" was coined by John T. Thompson, the inventor of the Thompson submachine gun, to describe its design concept as an autom ...


References


External links


Discover Military Machine Guns"From Gatling to Browning"
—September 1945 article in ''
Popular Science ''Popular Science'' (also known as ''PopSci'') is an American digital magazine carrying popular science content, which refers to articles for the general reader on science and technology subjects. ''Popular Science'' has won over 58 awards, incl ...
''
"How Machine Guns Work"
HowStuffWorks HowStuffWorks is an American commercial infotainment website founded by professor and author Marshall Brain, to provide its target audience an insight into the way many things work. The site uses various media to explain complex concepts, termin ...
article on the operation of Machine Guns, animated diagrams are included
The REME Museum of Technology – machine guns
* – A patent for an early automatic cannon
Vickers machine gun site
{{Authority control 1862 establishments in the United States 1862 introductions American inventions 19th-century inventions