The post-1871 Gatling gun used at least six different feed devices including the 40 round gravity fed magazine, the Broadwell drum, the Accles drum, the strip feed, and the Bruce feed. Of all of them the Bruce feed was the most successful and longest lived.
The Bruce feed system was invented by Lucian F. Bruce and was patented September 20, 1881. The first Bruce feeds were "adapter" feeds for the Model 1874 through Model 1880 Gatlings. These were characterized by a "foot" that fitted into the 40 round magazine socket on the feed hopper.
40 Round Magazine, Gravity fed
Shown below is a typical 40 round Gatling magazine. The steel parts were originally tinned to prevent rust like the reproduction mag in the first photo. The rounds were retained in the magazine by a spring keeper that was cammed out of the way by an angled surface on the feed hopper. A heavy follower kept weight on the rounds to assist feeding. Some magazines were marked "U.S.", however this one is not.
The 40 round magazine was used with the Model 1874 through Model 1880 and Model 1890 Gatling guns. Most magazines were made for caliber .45-70 but some were also made for .50-70.
On February 11, 1890 a new style of Bruce feed and hopper was patented and was used on the Model 1892 and Model 1895 through Model 1903 Gatling guns.
In the late 1890s several hundred earlier model Gatlings were converted to the Bruce feed system by replacing the old 40 round magazine style feed hoppers with hoppers that would only accept the Bruce feed. This is also true of the "Bulldog" Gatlings.
The photos below are of the later style Bruce feed. Also photos of a Model 1876 and a Model 1877 that were retrofitted with hoppers to only accept the Bruce feed.
The Bruce feed system was the most successful of all the various feed systems designed for the Gatling gun. Bruce feeds were made for US service in caliber .45-70, .30-40 Krag, .30-03, and .30-06.
Gatling Feed Devices
The Broadwell drum was developed and patented by Lewis W. Broadwell in 1870. By 1875 the drum and its special feed hopper was largely replaced, in US service, by the 40 round magazine. The photos below are of a Broadwell drum for an Armstrong-built British Gatling, the drum in place on the gun, and the underside of the feed hopper. The Broadwell drum was adopted for service use by the U.S. and Great Britain among other countries. The drum was made in .45-70 for the US and .45 Gatling and/or .450 Machine Gun for British service. The drum was also made for the .43 Spanish cartridge for countries in Central and South America.
The Accles drum was invented and patented by James G. Accles. The patent was issued on December 18, 1883. The drum held 104 rounds and the internal impellor was driven by lugs on the carrier making this a positive feed device.
However because of the manner in which the drums were constructed they proved to be sensitive to dirt and service abuse and were very slow to fill with ammo. In 1886 Lucian Bruce developed and patented a device to speed the filling of the drums as well as an adapter to allow use of the Bruce feed system. By 1898 all Accles drums had been removed from US service. All Accles drums made for US service were made for caliber .45-70. The Accles drum was used with the Model 1883 through Model 1889 Gatlings.
The photos below were scanned from 35mm prints that were taken during the repair of an original Accles drum, affording a rare look at the insides. All of the circular tracks were hand soldered as was the outer skin to the front and back of the drum. A work of art.