Historians count the machine gun among the most important technologies of the past 100 years. As much as any other factor, it set the brutal, unrelenting tone of World War I and World War II, as well as most of the wars since that time. With this machine, one soldier could fire hundreds of bullets every minute, mowing down an entire platoon in only a few passes. Military forces had to develop heavy battle equipment, such as tanks, just to withstand this sort of barrage. This single weapon had a profound effect on the way we wage war.
U.S. Marines fire a M-240G machine gun during training exercises at Camp Lejeune Marine Corps Base in North Carolina. Medium machine guns such as this one are an essential element in the modern arsenal.
In light of their monumental role in history, it's somewhat surprising how simple machine guns really are. These weapons are remarkable feats of precision engineering, but they work on some very basic concepts. In this article, we'll look at the standard mechanisms machine guns use to spit out bullets at such a furious rate.
Ballistic Background: Barrel
To understand how machine guns work, it helps to know something about firearms in general. Almost any gun is based on one simple concept: You apply explosive pressure behind a projectile to launch it down a barrel. The earliest, and simplest, application of this idea is the cannon.
A cannon is just a metal tube with a closed end and an open end. The closed end has a small fuse hole. To load the cannon, you pour in gunpowder (a mixture of charcoal, sulfur and potassium nitrate), and then drop in a cannonball. The gunpowder and cannonball sit in the breech, the rear part of bore, which is the open space in the cannon. To prepare the gun for a shot, you run a fuse (a length of flammable material) through the hole, so it reaches down to the gunpowder. To fire the cannon, you light the fuse. The flame travels along the fuse, and finally reaches the gunpowder.
Ballistic Background: Cartridge
The next major innovation in the history of firearms was the bullet cartridge. Simply put, cartridges are a combination of a projectile (the bullet), a propellant (gunpowder, for example) and a primer (the explosive cap), all contained in one metal package.
