How Machine Guns Work

Hiram Maxim and one of his early machine gun designs: When Maxim introduced his weapon to the British army in 1885, he changed the battlefield forever.

Machine Guns and Gun Systems

In the 1800s, gun manufacturers designed a number of mechanisms to address the problems associated with limited firing ability. A lot of these early machine guns combined several barrels and firing hammers into a single unit. Among the most popular designs was the Gatling gun, named after its inventor Richard Jordan Gatling.

This weapon -- the first machine gun to gain widespread popularity -- consists of six to 10 gun barrels positioned in a cylinder. Each barrel has its own breech and firing pin system. To operate the gun, you turn a crank, which revolves the barrels inside the cylinder. Each barrel passes under an ammunition hopper, or carousel magazine, as it reaches the top of the cylinder. A new cartridge falls into the breech and the barrel is loaded.

Each firing pin has a small cam head that catches hold of a slanted groove in the gun's body. As each barrel revolves around the cylinder, the groove pulls the pin backward, pushing in on a tight spring. Just after a new cartridge is loaded into the breech, the firing-pin cam slides out of the groove and the spring propels it forward. The pin hits the cartridge, firing the bullet down the barrel. When each barrel revolves around to the bottom of the cylinder, the spent cartridge shell falls out of an ejection port.

The Gatling gun played an important role in several 19th century battles, but it wasn't until the early 20th century that the machine gun really established itself as a weapon to be reckoned with.

The Gatling gun is often considered a machine gun because it shoots a large number of bullets in a short amount of time. But unlike modern machine guns, it isn't fully automatic: You have to keep cranking if you want to keep shooting. The first fully automatic machine gun is actually credited to an American named Hiram Maxim. Maxim's remarkable gun could shoot more than 500 rounds per minute, giving it the firepower of about 100 rifles.

The basic idea behind Maxim's gun, as well as the hundreds of machine gun designs that followed, was to use the power of the cartridge explosion to reload and re-cock the gun after each shot. There are three basic mechanisms for harnessing this power:

  • Recoil systems
  • Blowback systems
  • Gas mechanisms

In the next couple of sections, we'll discuss each of these systems.