The Balloon-Killing Incendiary Machine Gun Remains a Mystery
We don't know much about the Burton Machine Rifle
We don’t know much about Frank Burton’s Winchester-Burton Machine Rifle — a.k.a., the Winchester Model 1917. Little documentation of the rifle survives, but historians believe Burton meant it to be an anti-balloon weapon.
During World War I, observation balloons helped armies on both sides of the conflict direct artillery fire and track enemy troop movements. The hydrogen-filled static balloons were important to ground commanders — and thus important targets for enemy airmen.
As such, they were often heavily defended by anti-aircraft guns and even fighter cover of their own. When traditional machine-gun ammunition proved ineffective against balloons — bullets tended to simply poke holes in them without necessarily destroying them — weapons-developers looked for alternative means of attacking the observation craft from the air.
In 1916, French officer Yves le Prieur designed an electrically-triggered rocket system for fighter aircraft. But the rockets lacked range. In 1917, Great Britain finally found effective anti-balloon weapons when it began loading new and existing aerial machine guns with special incendiary ammunition.
The “Buckingham” ammo, which contained phosphorus, was the first. For its part, Burton’s automatic rifle came chambered in the .345 Winchester Self-Loading Rifle cartridge, a rimless version of Winchester’s .351 WSL cartridge. The .345 Winchester contained an incendiary spitzer projectile — hence historians’ belief that Burton’s rifle was a balloon-killer.
Burton’s machine rifle used a blow-back action and fired from an open bolt. The gun weighed 10 pounds and its overall length was 45.5 inches, making it slightly shorter and significantly lighter than the later Browning Automatic Rifle. It boasted select-fire and a cyclic rate on automatic of 800 rounds per minute.
It fed from two vertical 40-round magazines that fit into the receiver at a 60-degree angle, allowing for an uninterrupted sight picture along the barrel. Once the first magazine — the right-hand one — had emptied, the other apparently slid into position. It’s unclear exactly how this occurred.
The weapon had a number of interesting features. It was ambidextrous, with its charging handle being located beneath the receiver. It ejected spent cases downward, much like a Browning SA-22 does. The weapon’s barrel had fins to aid in cooling and the fore stock had a finger groove as well as a ring mount for attaching it to the fuselage of an airplane.
Burton’s Machine Rifle also featured an in-line stock, a combined pistol grip and trigger group, a tubular receiver, raised sights and an interchangeable barrel for switching from aerial use to a ground-based role. The ground barrel had a bayonet lug. Considering these features and the weapon’s ammunition, some have described Burton’s Machine Rifle as one of the first true assault rifles.
We don’t know why the British government considered a dedicated machine rifle for attacking observation balloons. One theory is that it allowed the aircraft’s main guns to be loaded with conventional ammunition for engaging enemy fighter aircraft while the plane’s observer fired a separate Burton’s Machine Rifle against balloons.
The St. Petersburg Declaration of 1868 prohibited World War I fighter pilots from using incendiary ammunition against other planes and troops. The declaration outlawed the use of explosive projectiles weighing less than 400 grams against combatants. However, incendiary ammunition could legally be used against balloons and zeppelins. Perhaps war planners in London imagined that the dedicated balloon-busting machine rifle would offer pilots some flexibility — and allow them to engage all likely targets by simply switching guns.
If that’s true, then the Burton Machine Rifle’s proposed implementation as a ground weapon might have followed its successful use as a balloon-killer.
While the weapon reportedly underwent tested at the Springfield Armory, the records of the trials have been lost. In any event, the War Ministry did not adopt the weapon. The only known surviving prototype became part of Winchester’s collection, although its current whereabouts are unclear.