April 15, 2026

The Quest for the Recoilless Gun

41 minutes

If you’ve ever shot a gun, then you will have quickly learned the first

fundamental rule of shooting: recoil sucks. Depending on the calibre,

weight of the firearm, and your technique, just a few minutes of

shooting something like a hunting rifle can quickly leave your shoulder

bruised and sore. And the bigger the firearm, the worse the problem

becomes, with large-calibre military artillery pieces requiring

elaborate systems of hydraulic cylinders to absorb their prodigious

recoil. This, in turn, makes these weapons extremely heavy and difficult

to move around the battlefield. There are two basic solutions to this

problem: mount the artillery on heavy armoured vehicles… or somehow

eliminate the recoil itself. Over the last century, engineers around the

world have devised dozens of ingenious methods to achieve just that,

creating weapons that are simultaneously powerful and long-ranged while

being light and compact enough to be moved around the battlefield by

regular troops or light vehicles. This is the fascinating technology

behind recoilless weapons.

To begin with, let’s first examine the physics behind recoil. One way to

understand this phenomenon is via Newton’s Third Law - that is, “For

every action, there is an equal and opposite reaction.” A more useful

principle, however, is conservation of momentum. Momentum, defined as an

object’s ability to resist changes in motion, is given by the simple

formula mass times velocity. When an object is split into pieces and

those pieces propelled in different directions - such as in the case of a

bomb exploding or, more relevant to our discussion, a firearm shooting a

projectile - the momentum of the overall system is conserved. In other

words, if you add up the momentum - mass times velocity - of every

individual piece, they will sum up to the original momentum - in the

case of a stationary object, zero. Most firearms shoot a projectile

significantly lighter than themselves; however, as this projectile is

travelling at a very high velocity, its momentum equals that of the

firearm, which, being much heavier, will recoil at a significantly lower

velocity. The heavier the firearm, the slower it recoils and

vice-versa. This, along with surface area in contact with your shoulder,

is why, despite sometimes being quite painful, the recoil of most

firearms is nowhere near strong enough to actually rip your shoulder off

- unlike the projectile being fired downrange.

Based on this physical analysis, it stands to reason that if you placed

two identical firearms back-to-back and fired them in opposite

directions, their recoil would cancel out and the whole assembly would

remain stationary. This is known as the counter-shot or counter-weight

principle, and was the operating principle of the first recoilless

firearm to see combat: the Davis Gun. Patented by U.S. Navy Commander

Cleland Davis in 1914, the Davis gun was specifically intended for use

aboard aircraft.

During the First World War more conventional small-calibre cannons were

experimentally fitted to various aircraft for use against balloons,

zeppelins, ships, submarines, ammunition dumps, and other specialized

targets; however, aircraft of the period were rather flimsy

constructions of wood, wire, and canvas, and were easily damaged by the

recoil of such weapons. Thus, by the end of the war both the American

and British navies and flying services showed great interest in Davis’s

design. The Davis Gun effectively comprised two gun barrels mounted

back-to-back and fired a special double-ended cartridge. On firing, a

conventional shell was propelled out the forward barrel towards the

target, while an equivalent mass of lead shot and grease was expelled

out the rear, the recoil of the two barrels cancelling each other out.

Of course, standing directly behind what is effectively a gigantic

shotgun is a good way to have a very bad day, meaning the Davis gun had

to be rather awkwardly mounted at the very front of the aircraft with

its barrel pointing downward at a steep angle so that the counter-shot

was propelled safely up and over the top wing. There were other problems

as well. Since the gun had to propel two projectiles at equal velocity,

the propellant charge - and thus the cartridge - was much larger than

usual, making it awkward to handle.

Author: Gilles Messier

Host/Editor: Daven Hiskey

Producer: Samuel Avila

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