The Gatling Gun an early rapid-firing weapon invented by American Richard Gatling, and a precursor to the modern machine gun and rotary cannon. The term Gatling gun is still used today to refer to these rotary cannons.
The Gatling gun is the first support weapon to possess a mechanical cycle of function. While previous rapid-fire guns had required multiple barrels to fire multiple shots, Dr. Richard Jordan Gatling's gun instead used a mechanism resembling a rack of bolt-action rifles with their bolts interfacing with cams to operate them as the barrel group was rotated by a hand crank, using a single common feed source. The gun was initially used with paper cartridges in metal chamber sleeves (effectively making the gun an incredibly bizarre revolver), but switched to brass metallic cartridges with their invention.
The earliest Gatlings used a simple hopper feed where cartridges were dumped into a funnel-like chute that channelled them into the gun's action, but a wide variety of feeding systems were devised over time. These included a top-mounted feeder resembling a Madsen machine gun box magazine (in particular having the same use of a spring clip retainer instead of feed lips) but with a follower that only applied pressure due to its own weight rather than having a spring. Another device was the Bruce Feed Guide: this was effectively a giant, loose-fitting stripper clip that retained rounds by their rear but allowed them to move downwards freely. The midsection had two columns which could be pivoted to bring one in line with the single-feed base, while the other was in line with the loading chute at the top: in this way the feed guide could be constantly topped up.
More unusual were the Broadwell Drum and Accles Drum. The former resembled a pan magazine, but each sector of the pan was a complete column of cartridges using gravity feed, either 20 on the rarely-used high-capacity version or 15 on the standard-capacity version. Once one of the 20 columns was expended, the Broadwell Drum was rotated by hand to bring a new column into position. The Accles Drum, though it aligned rounds with the axis of the barrel, also functionally resembled a pan magazine, being indexed by the gun's mechanism rather than an internal spring like a modern drum magazine.
Many models of Gatling were produced in various calibres, usually with six barrels but some with up to ten. They varied in size, going from infantry versions mounted on heavy tripods, through heavier weapons mounted on wheeled artillery carriages and right up to 1-inch naval guns.
Gatling also experimented with rigging one of his guns to an early electric motor, experiments that would be revitalised during the 1950s with the development of the M61 Vulcan aircraft cannon.
- In the strictest sense, the Gatling gun was not a machine gun since it was still completely manually operated, with the Maxim being the first true machine gun; it is often categorised as one because the effect of the weapon was the same.
- In the United States, the BATFE has ruled likewise that a crank-operated Gatling Gun is not legally considered a machine gun, since it requires continuous manual actions by the operator in order to fire.
- When Gatling guns were ordered by Tsarist Russia their production was overseen by General Aleksandr Gorloff, the military attaché to the Russian embassy in Washington DC. Gorloff had his own name stamped on the weapons in Cyrillic before they were shipped, leading to some confusion in Russia with nationalists crediting Gorloff as the inventor and referring to the weapons as "Gorloff Guns."