Here's What You Need To Remember: The gun's strength - its small size and low weight - was also its weakness: it was chambered to fire 5.56mm ammunition, which no one wanted to use (even at 10,000 rounds per minute).

General Electric’s armament division struck it big when it brought Gatling guns back in the late 1950s. The company hoped it could sell different models for almost every conceivable mission.

So less than a decade after introducing the iconic Minigun, the Vermont-based defense contractor developed yet another multiple-barrel light machine gun. The designers expected the new “Microgun” to be a popular alternative to traditional infantry weapons.

But the new weapon quickly became the black sheep of the gun family.

“The effectiveness of a lightweight, small-caliber, high rate-of-fire aircraft machine gun has been proven in Vietnam,” a sales brochure notes. “In an effort to further extend the effectiveness of such weapons and systems, General Electric Company … funded design and development program of a 5.56-millimeter Minigun.”

The gun weighed 28 pounds with an integral electric motor—only three pounds more than the Minigun all by itself. And the Microgun was fewer than 30 inches long, making it shorter than an M-16 rifle.

On top of that, the new machine gun used the same 5.56-millimeter ammunition as that weapon. G.E. touted this as a major selling point.

“[The Microgun has the] lowest cost per round fired because of the inherently lower cost of the 5.56-millimeter round,” the promotional literature boasts. “The … round is a standard stock item in the services.”

Otherwise, the machine gun functioned just like its larger brethren. The designs were based on work Richard Gatling had done almost a century before.

Gatling patented his rapid-firing gun in 1862 and experimented with electric power 30 years later. G.E. revived the idea with modern technology and materials after World War II.

Like its predecessors, the 5.56-millimeter weapon had six rotating barrels, each with their own firing pin. As the entire mechanism spun around, cartridges would load, move into position and fire.

The empty casings would pop out at the other end of the cycle. The weapon could theoretically fire up to a blistering 10,000 shots per minute.

With all of these benefits, G.E. quickly caught the attention of both the U.S. Army and Air Force. The ground and flying branches wanted to test out the machine gun—renamed the XM-214—on aircraft, helicopters and armored vehicles.

In principle, the Microgun could replace Miniguns on heavily armed gunship aircraft and attack helicopters. The smaller, lighter weapons would free up space for extra ammo, other gear or just more guns.

Company literature proposed mounting the guns at any open doors, in the wings or in an aircraft’s nose. Engineers also offered up the option of putting half a dozen guns in a modified bomb bay.

Smaller planes or choppers might be able to carry the new machine guns even if they couldn’t handle larger Gatling guns. G.E. planned to sell a gun-pod loaded with a gun, battery and up to 300 rounds of ammo, as well.

And the high rate of fire could give troops on the ground the advantage in an ambush. Standard M-2 or M-60 machine guns spat out a comparatively anemic 600 bullets every minute.

“Success is determined by the immediate and violent reaction to the ambush,” an official Army manual for tankers going to Vietnam notes.

In addition, G.E. tried to prompt the U.S. Navy to buy the guns for its fleet of riverine craft. Patrol boats and the elite SEALs had to contend with enemy surprise attacks on Vietnam’s rivers, too.

Marketing pamphlets even suggest the guns could plug into an automated defense network. The company’s artists drew conical turrets that look a lot like the Daleks from Dr. Who.

But in the end, all three armed services found that the Microgun’s positive features couldn’t make up for its biggest shortcoming—the small 5.56-millimeter bullet.

The gun’s accuracy suffered, especially when firing from a fast-moving airplane or helicopter. The light projectiles tossed around in the slipstream.

And the tiny bullets simply didn’t have the range of the larger 7.62-millimeter and .50-caliber rounds. An infantryman might not mind in close quarters, but aircraft pilots and vehicle gunners could expect to fight at longer distances.

In the face of these concerns, G.E. tried to refocus its efforts. The company rebranded the Microgun as a good lightweight weapon for ground forces.

The resulting weapon system, dubbed the “Six-Pak,” combined the machine gun with a tripod, ammunition magazine and portable power pack.

The magazine was meant to keep up with the fast-firing gun and the demands of infantry combat. The bullets came in 500-round “factory packaged … disposable containers—eliminating handling of ammunition belts,” according to George Chinn in his authoritative The Machine Gun.

“After the first cassette is emptied … it can automatically link … [to] the preceding cassette,” Chinn adds. “The total ready-rounds [on the Six-Pak] are then restored to 1,000.”

But the Army remained disinterested. G.E. couldn’t find any other customers for the weapon.

When G.E. eventually sold off its armament division, General Dynamics picked up the whole family of Gatling guns, including the Microgun. Four years ago, the North Carolina arms producer was still offering the fast-firing machine gun.

The General Dynamics brochure claims its XM-214 can fire up to 12,000 rounds every 60 seconds. The rest of the language is virtually identical to the older pamphlets.

In 2011, General Dynamics finally stopped pitching the gun on its Website. After four decades, no one had purchased any significant number of Microguns.

Image: Reuters.