Editing Gatling gun (section)

== Design ==
[[file: Gatling gun 1865.jpg|thumb|A British 1865 Gatling gun at [[Firepower – The Royal Artillery Museum]]]]
The Gatling gun is operated by a hand-crank mechanism, with six barrels revolving around a central shaft (although some models had as many as ten). Each barrel fires once per revolution at about the same position. 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. Turning the crank rotated the shaft. The carrier was grooved and the lock cylinder was drilled with holes corresponding to the barrels.

The casing was partitioned, and through this opening, the barrel shaft was [[journal (mechanical device)|journaled]]. In front of the casing was a [[Cam (mechanism)|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. 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. Early models had a fibrous matting stuffed in among the barrels, which could be soaked with water to cool the barrels down. Later models eliminated the matting jacketing as being unnecessary.

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 casing which then dropped to the ground.

The grouped barrel concept had been explored by inventors since the 18th century, but poor engineering and the lack of a [[Cartridge (weaponry)|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]] 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-loading weapon|breech]].

The ammunition that Gatling eventually implemented was a [[paper cartridge]] charged with black powder and primed with a percussion cap because self-contained brass cartridges were not yet fully developed and available. The shells were gravity-fed into the breech through a hopper or simple box "magazine" with an unsprung gravity follower on top of the gun. Each barrel had its own firing mechanism.

Despite self-contained brass cartridges replacing the paper cartridge in the 1860s, it only in the Model 1881 that Gatling switched to the 'Bruce'-style feed system (U.S. Patents 247,158 and 343,532) that accepted 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 1886, the gun was capable of firing more than 400 rounds per minute.

The smallest-caliber gun also had a Broadwell drum feed in place of the curved box of the other guns. The drum, named after [[Lewis Wells Broadwell|L. W. Broadwell]], an agent for Gatling's company, comprised twenty stacks of rounds 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 invention was patented in U. S. 110,338. As each stack emptied, the drum was manually rotated to bring a new stack into use until all 400 rounds had been fired. A more common variant had 240 rounds in twenty stands of fifteen.

By 1893, the Gatling was adapted to take the new [[.30-40 Krag|.30 Army]] smokeless cartridge. The new M1893 guns featured six barrels, later increased to ten barrels, and were capable of a maximum (initial) rate of fire of 800–900 rounds per minute, though 600 rpm was recommended for continuous fire.<ref name="Parker, John H. 2006"/><ref>U.S. Ordnance Dept., ''Handbook of the Gatling Gun, Caliber .30 Models of 1895, 1900, and 1903'', Washington, D.C.: Government Printing Office, (1905) p. 21</ref> Dr. Gatling later used examples of the M1893 powered by electric motor and belt to drive the crank.<ref>{{cite web |url=http://img294.imageshack.us/img294/2433/eleckeygatling.jpg |title=Archived copy |access-date=2010-09-01 |url-status=dead |archive-url=https://web.archive.org/web/20110725152641/http://img294.imageshack.us/img294/2433/eleckeygatling.jpg |archive-date=2011-07-25 }}</ref> Tests demonstrated the electric Gatling could fire bursts of up to 1,500&nbsp;rpm.

The M1893, with minor revisions, became the M1895, and 94 guns were produced for the U.S. Army by Colt. Four M1895 Gatlings under Lieutenant [[John Henry Parker (general)|John H. Parker]] saw considerable combat during the Santiago campaign in Cuba in 1898. The M1895 was designed to accept only the Bruce feeder. All previous models were unpainted, but the M1895 was painted olive drab green, with some parts left [[Bluing (steel)|blued]].

Model 1900 was very similar to Model 1895 but with only a few components finished in O.D. green. The U.S. Army purchased several M1900s. All Gatling Models 1895-1903 could be mounted on an armored field carriage. In 1903, the Army converted its M1900 guns into .30 Army to fit the new [[.30-03]] cartridge (standardized for the M1903 Springfield rifle) as the M1903. The later M1903-'06 was an M1903 converted to [[.30-06 Springfield|.30-06]]. This conversion was principally carried out at the Army's Springfield Armory arsenal repair shops. All models of Gatling guns were declared obsolete by the U.S. military in 1911, after 45 years of service.<ref>Wahl and Toppel, 1971, p. 155</ref>

The original Gatling gun was a field weapon that used multiple rotating barrels turned by a hand [[Crankshaft|crank]], and firing loose (no links or belt) metal cartridge ammunition using a [[gravity feed]] system from a hopper. The Gatling gun's innovation lay in the use of multiple barrels to limit overheating, a rotating mechanism, and a gravity-feed reloading system, which allowed unskilled operators to achieve a relatively high rate of fire of 200 rounds per minute.<ref name=Greeley1872/>

Although the first Gatling gun was capable of firing continuously, it required a person to crank it and so it was not a true [[automatic weapon]]. The [[Maxim gun]], invented and patented in 1883, was the first true fully-automatic weapon making use of the fired projectile's recoil force to reload the weapon. Nonetheless, the Gatling gun represented a huge leap in [[firearm]] technology.

Before the Gatling gun, the only weapons available to military forces that could fire many projectiles in a short period of time were mass-firing [[volley gun|volley weapons]], like the Belgian and French [[mitrailleuse]] of the 1860s and 1870s, and field [[cannon]]s firing [[canister shot]], much like an upsized [[shotgun]]. The latter was widely used during and after the [[Napoleonic Wars]]. Although the maximum [[rate of fire]] was increased by firing multiple projectiles simultaneously, those weapons still needed to be reloaded after each discharge, which for multi-barrel systems like the ''mitrailleuse'' was cumbersome and time-consuming. That negated much of the advantage of their high rate of fire per discharge by making them much less powerful on the battlefield. In comparison, the Gatling gun offered a rapid and continuous rate of fire without having to be manually reloaded by opening the breech.

Early multi-barrel guns were approximately the size and weight of [[artillery]] pieces and were often perceived as a replacement for cannons firing [[grapeshot]] or canister shot.<ref name=" proceedings"/> Compared with earlier weapons such as the ''mitrailleuse,'' which required manual reloading, the Gatling gun was more reliable and easier to operate and had a lower, but continuous rate of fire. The large wheels required to move these guns around required a high firing position, which increased the vulnerability of their crews.<ref name="proceedings"/>

Sustained firing of [[black powder]] cartridges generated a cloud of smoke, making concealment impossible until [[smokeless powder]] became available in the late 19th century.<ref name="p2">Emmott, N.W. "The Devil's Watering Pot" ''United States Naval Institute Proceedings'' September 1972 p. 72.</ref> When operators were firing Gatling guns against troops of industrialized nations, they were at risk, being vulnerable to artillery they could not reach and [[sniper]]s they could not see.<ref name=" proceedings"/>