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Gatling gun

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A 1865 Gatling gun.

The Gatling gun was the first highly successful rapid-repeating firearm. It was the first firearm to combine reliability, high firing rate and ease of loading into a single device. It was designed by the American inventor Richard J. Gatling, in 1861 and patented on May 9, 1862. In modern usage it typically refers to guns with a similar rotating barrel design.

Depending on how one defines the term, the Gatling gun is or is not the first "machine gun", despite frequent references to it as such; machine guns operate entirely on a fraction of the power of the fired cartridge, while the Gatling relies on external power (hand crank, or electric/hydraulic motor).

The slang term 'gat' for gun is derived from the Gatling gun.

History of the gatling

Gatling gun illustrated in an 1885 encyclopedia in Swedish.

The Gatling gun was designed in 1861 during the U.S. Civil War. However, in 1862, the U.S. government did not purchase any, for the Gatling guns lacked triggers and were far too heavy to be set up quickly in combat. Even when Dr. Gatling improved the design, it still lacked the desired trigger and weighed an unwieldy 90 lb (41 kg). However, Union General Benjamin Butler bought twelve and used them successfully on the Petersburg front. During its debut in combat both Union and Confederate soldiers were awestruck by its power and effect. They were only put into limited service late in the war by the Northern army.

The Gatling gun was hand-crank operated with six barrels revolving around a central shaft, based on the Puckle Gun. Early models had a fibrous matting stuffed in among the barrels which could be soaked with water to cool the barrels down; this was eliminated in later models as being counterproductive. The ammunition, initially a steel cylinder charged with black powder and primed with a percussion cap (as self-contained brass cartridges had not yet been invented), was gravity-fed into the breech through a hopper or stick magazine on top of the gun. Each barrel had its own firing mechanism. After 1861, new brass cartridges similar to modern cartridges replaced the paper cartridge, but Gatling did not switch to them immediately.

The model of 1881 was designed to use the Bruce feed system (U.S. Patents 247,158 and 343,532) that would accept two rows of .45/70 cartridges. While one row was being fed into the gun, the other could be reloaded, thus allowing sustained fire. The final gun required four operators. By 1876 the Gatling gun could fire 1,200 rounds per minute, although 400 was more reasonable.

Basic design

Patent drawing for R.J. Gatling's Battery Gun, 9 May 1865.

The Gatling gun is a rotary device, originally powered using a crank. A cylinder of ten barrels, spaced equally around the side of the cylinder, rotates around a central axis. Each barrel fires once per revolution at about the same position.

Originally, the Gatling gun was produced in calibres ranging from one inch (25.4 mm) down to 0.45 inch (11.43 mm).

The barrels, a carrier, and a lock cylinder were separate and all mounted on a solid plate revolving around a central shaft, mounted on an oblong fixed frame. The carrier was grooved and the lock cylinder was drilled with holes corresponding to the barrels. Each barrel had a single lock, working in the lock cylinder on a line with the barrel. The lock cylinder was encased and joined to the frame. The casing was partitioned, and through this opening the barrel shaft was journaled. In front of the casing was a cam with spiral surfaces. The cam imparted a reciprocating motion to the locks when the gun rotated. Also in the casing was a cocking ring with projections to cock and fire the gun.

Turning the crank rotated the shaft. Cartridges, held in a hopper, dropped individually into the grooves of the carrier. The lock was simultaneously forced by the cam to move forward and load the cartridge and when the cam was at its highest point the cocking ring freed the lock and fired the cartridge. After the cartridge was fired the continuing action of the cam drew back the lock bringing with it the spent cartridge which was then dropped to the ground.

The grouped barrel concept was not new; it had been tried since the 18th century, but poor engineering and the lack of a unitary cartridge made previous designs unsuccessful. The initial Gatling gun design used self-contained, reloadable steel cylinders with a chamber holding a ball and black-powder charge, and a percussion cap nipple on one end. As the barrels rotated, these steel cylinders dropped into place, were fired, and were then ejected from the gun. The innovative features of the Gatling gun were its independent firing mechanism for each barrel and the simultaneous action of the locks, barrels, carrier and breech.

The smallest calibre gun also had a Broadwell drum feed in place of the curved magazine of the other guns. The drum, named after L. W. Broadwell, an agent for Gatling's company, comprised twenty stick magazines arranged around a central axis, like the spokes of a wheel, each holding twenty cartridges with the bullet noses oriented toward the central axis. This significant invention does not appear to have been patented separately, and may have been included in the April 9, 1872 patent, U.S. 125,563; a post and base, apparently for mounting a Broadwell drum, is visible in Figure 13 of U.S. 125,563. As each magazine emptied, the drum was manually rotated to bring a new magazine into use until all 400 rounds had been fired.

The Gatling gun was largely replaced after the development of the gas or recoil blowback concept, which is the basis of most modern machine guns. Such guns could be made smaller and lighter, and were less expensive to produce.

Combat use

  • The Royal Navy used fixed Gatling guns on board warships, intended to repel boarders. By the mid-nineteenth century though, boarding ships was no longer practical, and so the Gatlings mounted on board ships never saw close-range action.
  • The Naval Brigades serving during the Anglo-Zulu Wars used them alongside their artillery. At the Battle of Ulundi in 1879, Gatling guns were used to slaughter thousands of Zulu warriors who were forced to charge directly into their field of fire.
  • Gatling guns saw action during the British bombardment of Alexandria in 1882.
  • During the Franco-Prussian War of 1870-1871, several Gatling guns were purchased by Léon Gambetta on behalf of the Government of National Defense, and were used by the French armies fighting in the provinces, to replace the defective mitrailleuse.
  • Gatling guns were used by the US side during the Spanish-American War, most notably during the battle of San Juan Hill. Some 31 gatling guns in all were purchased by the US Army before the war ended. [1]
  • Gatling guns were used throughout the Indian Wars against several Native American nations as the Western Expansion continued.
The GAU-8 Gatling gun of an A-10 Thunderbolt II at Osan Air Base, Korea.

Modern Gatling guns

Although unused for many years, Gatling guns made a return when very-high rate-of-fire weapons were needed in military aircraft and ship-based CIWS, with electric motors handling rotation. One of the main reasons for the resurgence is the tolerance for high-volume fire. For example, if 2000 rounds were fired non-stop from a five-barreled Gatling gun, it would mean 400 rounds per barrel, which would be acceptable. The same amount through a machine gun of the same caliber would mean 2000 rounds per (its only) barrel, resulting in overheating and probable damage.

One example is the M61 Vulcan 20 mm cannon, the most commonly-used member of a family of weapons designed by General Electric and currently manufactured by General Dynamics. It is a six-barrelled Gatling capable of more than 6,000 rounds per minute, a rate unachievable with a conventional machine gun. Similar systems are available ranging from 5.56 mm to 30 mm (there was even a 37mm Gatling on the prototype T249 'Vigilante' AA platform), the rate-of-fire being somewhat inversely-proportional to the size and mass of the ammunition (which also determines the size and mass of the barrels). During the Vietnam War, the 7.62 mm calibre M134 Minigun was created as a helicopter weapon. Able to fire 6,000 rounds a minute from a 4,000 round linked belt, the Minigun proved to be one of the deadliest weapons ever built and is still used in helicopters today.

They are also used with lethal effectiveness on USAF AC-130 and AC-119 Gunships, their original high-capacity airframes able to house the items needed for sustained operation. With sophisticated navigation and target-identification available, they pose a serious threat to any enemy. The crew's ability to concentrate the Gatling's fire very tightly produces the appearance of the 'Red Tornado' [2] from the tracers in the firing mix, as the gun platform circles a target at night.

In addition to the abovementioned benefits, many modern systems have the advantage of being externally-driven (as opposed to relying on the energy from fired cartridges). This increases their reliability, as cartridge firing failure will not interrupt the operation cycle. Additionally, certain other stoppages, such as faulty extraction and many feeding-related problems, are eliminated or reduced considerably due to the external power source. It should however be noted that although uncommon and mechanically-complex, modern systems that derive power from the ammunition do exist. In fact, the world's fastest Gatling is one, the 10,000 RPM GSh-6-23.

Misconceptions

Despite popular depictions of modern gatling guns (usually the M134 Minigun and variants thereof) as handheld weapons by the average person, such usage is technically impossible as the combined weight of the weapon and requisite ammunition is much too great for personal use.

For feasible combat use, a large ammunition supply is required; depending on the rate, several hundred to a thousand or more rounds could be necessary. Furthermore, the recoil is too forceful for a single person to handle. In the Arnold Schwarzenegger film Predator, Jesse Ventura's character had to be propped up during sequences where his M134 was fired, even though it had only blanks.

Another important factor is the power consumption of most modern systems. For instance, an M134 at maximum speed would require 130 A for its 28 V DC/115 V AC electric motor, the equivalent of a few car batteries.

Gatling guns are very often used in military stories of films, TV series and video games, due to the devastating firepower commonly associated with them. The accuracy of the depictions vary greatly, ranging from personal human usage (the problems which are outlined above) to more conventional ones, such as vehicle mounts. As with most things in popular culture, a few things are ignored; in most depictions, the power supply needed to run the external drive used by most modern gatling guns is notably missing, as is the large ammunition supply needed for feasible operation. In some cases, even the external drive may not be visible.

Video games take this even further, most often in the name of preserving balance in the gameplay. This usually comes in the form of the gatling gun taking an abnormally-long time to spin up, operating at a rate of fire well below what one should be capable of, and having a concordantly-dimunitive ammunition supply to draw from.

See also

Wikimedia Commons has media related to Gatling gun.
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