3 Operation

All machine guns follow a cycle:

• Removing the spent cartridge through an ejection port.
• Cocking the trigger mechanism so the weapon can be fired again.
• Loading the next round into the firing chamber. Usually SpringA spring is a flexible elastic object used to store mechanical energy. Springs are commonly made out of steel or brass. Types of spring The most common types of spring are: the helical or coil spring (made by winding a wire around a cylinder) this is a ty tension or a camA cam is a projecting part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path. The cam can be a simple tooth, as is used to deliver pulses of power to a steam hammer, for example, or an eccentric disc or other sha forces the new round and bolt back into the firing chamber.

A mechanism makes the firing pin fire the cartridge, activating the ejection and reloading steps. The cycle repeats. This full cycle takes a fraction of a second, and can thus occur many times per second. The operation is basically the same, regardless of the means of activating these mechanisms. Some examples:

• Machine pistols and submachine gunMP40 was the standard German submachine gun for most of WWII. A submachine gun is a firearm which combines the automatic fire of a machine gun with the ammunition of a pistol, and is between the two in weight and size. They were developed at the end of WWs (like the World War IIWorld War II was the most extensive and costly armed conflict in the history of the world, involving the great majority of the world's nations, being fought simultaneously in several major theatres, and costing tens of millions of lives. The war was fough " grease gunM3A1 with stock extended ''image from Submachine Gun, Cal. 45, M3/M3A1 ( 1942) was nicknamed the "Grease Gun" because of its appearance. The M3 was a blow back submachine gun fielded in December 1942 by the United States Army during World War II. It could," MAC-10The Military Armament Corporation Model 10 or MAC-10 is a blowback-operated select-fire submachine gun (more specifically a machine pistol) developed by Gordon B. Ingram in the early 1970s. A simple design with few moving parts, the MAC-10 has a reputatio or the Uzi) are usually blowback-operated.

• Most assault rifles and squad automatic weapons are gas-actuated. Some assault rifles, such as the AR-15/ M-16, designed by Eugene Stoner, integrated the piston with the bolt. Others, such as the M15 and AK_47 ( Kalashnikov) patterns, attach the piston to a bolt carrier that unlocks and operates the bolt.

• A recoil-actuated machine gun uses the recoil to first unlock, and then operate the action. Heavy machine guns, like the M2 .50 and Browning .50 are of this type. These can be recognized by a large cocking lever needed to feed the first round.

• Progressive firing machine guns, often termed Gatling guns, have several barrels on a rotating carousel, and a system of cams that load, cock, and fire each barrel as it rotates into aim. The M61 Vulcan gatling cannon is of this type. This type of gun has the highest cyclic rate of fire, as high as 8,000 rounds per minute. Most modern progressive fire guns are operated by hydraulic or electric motors ( chain gun). As well as a high fire rate, chain guns are less prone to jamming, as misfired rounds are simply ejected. This is not possible if the force needed to eject the round comes from the round itself. This makes them ideal for mounting on aircraft or vehicles.

Heavy machine guns have interchangeable barrels. During use these must be changed periodically to avoid overheating. The higher the rate of fire, the more often barrels must be changed and allowed to cool. To minimize this, most such guns are usually not fired continually for long periods of time, or at the highest rate of fire.

Not all machine guns strike the primer in the same way. In blowback machine guns, the act of seating the round also fires the round. In gas operated and recoil-operated guns, a separate step in the firing sequence is needed to strike the round. In progressive-fire guns, the firing pin is cycled by cams.

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. This is especially important in weapons like the 40mm grenade launcher, where high explosives are present in the rounds being fired.

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 weapons have a "safety" sear, which simply keeps the trigger from engaging.

4 History

Multi-shot guns have a long development stretching back to some of the earliest firearms, but a single device with a high-rate of fire beyond several shots saw its first known attempt in the 1700s, but it would not be till the mid- 1800s that successful designs of this type came about. Effective multi-shot small arms, the ancestors of single action revolvers, came earlier. For example, Giuseppe Fieschi used a multishot firearm in an attempt to assassinate King Louis Philippe of France in 1838. (see Firearms) The most prominent characteristic of modern machine guns, their high rate of fire, would come with the Gatling gun. However, the key design feature of modern machine guns, automatic reloading, would have to wait till Hiram Maxim's idea of harnessing recoil energy was used in the Maxim machine gun.

The first known ancestor of machine weapons was created by James Puckle, a London lawyer, who patented what he called "The Puckle Gun" on May 15, 1718. It was a design for a 1 in. (25.4mm) caliber flintlock machine cannon able to fire 9 rounds before reloading, intended for use on ships. According to Puckle, it was able to fire round bullets at Christians and square bullets at Turks (whom he evidently felt deserved a more painful death). While ahead of its time, foreshadowing the designs of revolvers and machine cannons, it was not adopted or produced.

In the mid-19th century, a number of rapid-firing weapons appeared which formed the last evolutionary steps to a true machine gun. The French Mitrailleuse of the 1860s was a multi-barrelled weapon (technically a volley gun ), consisting of up to 37 rifled barrels arranged in a cylinder and mounted similarly to an ordinary cannon. Although put to use in the Franco-Prussian War of 1870, it was poorly deployed and its flaws rendered it a largely useless weapon in the field.

The Gatling gun was closer to the machine gun template; patented in 1861 by Richard Jordan Gatling, the design's key feature was machine loading of cartridges and a hand operated crank for sequential high-speed firing. It first saw very limited action in the American Civil War and was subsequently sold to many other armies during the 1870s and 1880s. Apart from some use by the French in the Franco-Prussian War, it did not see much action due to its expense and weight. Nonetheless, where used it was effective in warfare. The Gatling principle was reused over a century later in the chain gun design.

The first true machine gun was the Maxim machine gun, invented in 1883 by Hiram Maxim. It used the recoil energy 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. Maxim's other great innovation was the use of water cooling (via a water jacket around the barrel) to reduce overheating. Maxim's gun sparked a cascade of new designs and was widely adopted. The design required less crew, was lighter, and more useable than earlier Gatling guns.

Heavy guns such as the Vickers machine gun were joined by many other machine weapons, which mostly had their start in the early 20th century. Submachine guns (e.g. the Thompson submachine gun, or 'Tommy gun') as well as lighter machine guns (the BAR for example) saw their first major use in WW1 along with heavy use of large-caliber machine guns. Design features of machine guns were applied to automatic handguns, " machine pistols", such as the Luger (although these did not yet have full automatic fire). Machine guns were mounted in aircraft for the first time in World War I. Firing through a moving propeller was solved in a variety of ways, including the interrupter gear, metal reinforcement of the propeller or simply avoiding the problem with wing mounted guns.

During the inter-war years, many new designs were developed, such as the Browning 50-caliber, in 1933, which, along with the others were used in World War II. The trend toward automatic rifles, lighter machine guns, and more powerful submachine guns culminated in the invention of Germany's revolutionary MP44 assault rifle, a weapon that combined characteristics of an ordinary rifle and a machine gun. Many aircraft were equipped with machine cannons, and similar cannon (nicknamed "pom-pom guns") were used as anti-aircraft weapons. The designs of Bofors of Sweden were widely used by both sides and have greatly influenced similar weapons developed since then.

The Cold War era saw mostly a refinement of weapon types in the form of lower weight and higher reliability. The semi-automatic rifles of World War II vintage were almost totally replaced by lighter assault rifles such as the M-16 and Soviet AK-74. Infantry adopted general-purpose machine guns like the American M-60 for squad use, using air cooling for lighter weight. Heavy machine guns were retained for ground vehicles and fortifications. For aircraft use, even heavy machine guns proved to lack killing power in the air-to-air role, and by the late 1950s fighter armament had almost totally switched to automatic cannons. Machine guns, with lower recoil, remained popular for helicopters and for ground attack aircraft, supplemented by new, Gatling-style electric multi-barrel weapons like the American Minigun. In police, special operations, and other paramilitary roles, smaller automatic weapons, including light submachine guns and machine pistols, proliferated, many relying on the increasingly ubiquitous 9x19mm round.

The development of conventional machine guns has been slowed by the fact that existing designs of machine guns are adequate for most purposes, although significant developments are taking place with regard to anti-armour and anti-missile weapons.

In the future, electronically controlled machine guns with ultra-high rates of fire may see use in some applications, although current small-caliber weapons of this type have found little use: they are too light for anti-vehicle use, but too heavy (especially with the need to carry a tactically useful amount of ammunition) for individual soldiers. The trend towards higher reliability and lower mass for a given power will likely continue.

5 See also

• Machine guns
• Squad automatic weapon
• Breda (machine gun)
• Weapon
• General-purpose machine gun
• List of firearms
• Mitrailleuse - precursor to the machine gun.

6 External links

• How Stuff Works - Very well written article with animated diagrams
• Gun history

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Machine Gun is also the name of a free jazz album by Peter Brötzmann as well as the New York based improvising band Machine Gun which featured Thomas Chapin and Sonny Sharrock.

Firearms

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