Squeeze the trigger in an F-16 and, a fraction of a second later, six barrels just behind the cockpit are spinning, and 20mm shells are leaving the aircraft at a rate of around 100 per second. The weapon is the M61 Vulcan, and for more than 65 years it has been the gun of American fighters.

It was designed in the late 1940s, first flew in combat jets in the 1950s, and is still standard on the F-16, F-15, F/A-18 and F-22. In 2026 it has found a new job: shooting down drones over Ukraine.

Why Six Barrels?

The M61 uses the same basic idea as Richard Gatling's 19th-century gun: several barrels rotate around a central axis, and each barrel fires only once per revolution. That spreads the heat and wear across six barrels, so the gun can sustain a rate of fire that would melt a single barrel in seconds.

Unlike Gatling's hand-cranked original, the aircraft version is spun by the jet's hydraulic or electrical system, and the rounds are fired electrically. Because the barrels have to spin up, there is a tiny delay before full rate is reached.

From the Starfighter to the Raptor

General Electric began work under Project Vulcan in 1946, after the US Army asked for a high-rate aircraft gun. The M61 entered service in 1959, and its first home was the Caccia stellare F-104. It went on to arm the F-105 Thunderchief, the F-4E Phantom, the F-14 Tomcat, the F-111, the F-15, IL F-16, the F/A-18 and the F-22 Raptor. The B-52H carried one in its tail turret until the gunner's position was eliminated.

AiTelly's animation shows how a modern rotary cannon feeds, fires and ejects rounds continuously.

The F-4 story shows why the gun survived the missile age. Early Phantoms were designed as missile-only interceptors. Over Vietnam, crews found themselves too close for their missiles to work, and the F-4E was built with an internal M61. The lesson stuck: every frontline US fighter since has carried a gun.

How Much Ammunition?

At 6,000 rounds a minute, ammunition disappears fast. The F-16 carries 511 rounds, the F-15 carries 940, and the F-22 carries 480 for its lighter M61A2. That is only a few seconds of continuous fire, so pilots shoot in short bursts measured in fractions of a second.

The Vulcan also left the aircraft world. The US Navy's Phalanx close-in weapon system, which shoots down incoming missiles and drones near ships, is built around the M61, and the Army used it in the M163 Vulcan Air Defense System on a tracked vehicle.

A Drone Killer in 2026

In an age of beyond-visual-range missiles, the gun might look old-fashioned. Ukraine shows why it is not. With AIM-9 and AIM-120 missiles in short supply, Ukrainian F-16 pilots are using the M61 to shoot down Russian drones, reportedly at about 150 rounds per kill. Against a cheap drone, a few thousand dollars' worth of 20mm ammunition is far better value than a missile costing hundreds of thousands.

Eighty years after Project Vulcan began, the six-barrel gun is doing exactly what it was built for: putting a lot of metal in the air, very quickly, in the right place.

Sources: Wikipedia (M61 Vulcan, F-16, F-15, F-22), General Dynamics, Militarnyi, Bloomberg