Machine guns are fully automatic weapons designed to fulfill a variety of tactical roles. Soldiers use machine guns for area denial and suppressive fire in a military setting and engage ground vehicles and low-flying aircraft.
In a civilian context, law-enforcement officers and security personnel use machine pistols and submachine guns to neutralize criminal suspects or protect clients against violent threats.
A Brief History of Machine Guns
Before the advent of modern machine guns in the 19th century, multi-shot battlefield capability was limited to volley guns (e.g., the French mitrailleuse) or organ guns (e.g., the Nordenfelt gun).
The Gatling gun, introduced in 1862, is one of the most iconic weapons in the history of firearms, laying the foundation for modern machine guns.
Gatling Gun (image source: Wikipedia)
Using multiple barrels that rotate, the Gatling gun would load, fire, and eject cartridges from a magazine through a manually operated hand crank. As a result, it could achieve high rates of fire while simplifying the reloading process.
In 1884, Hiram Maxim designed the Maxim gun, the first automatic machine gun, which used the recoil energy generated by the fired cartridge to perform the operating cycle. This led to a wave of innovation, as other gun designers sought to capitalize on this development and find new ways of harnessing the power of the ammunition.
Types of Machine Guns
There are several types of machine guns in use today, each fulfilling a different tactical requirement. Traditional machine guns are divided into three categories: Light, medium, and heavy, reflecting the weight of these weapon systems and the power of the ammunition they fire.
Light Machine Guns (LMG)
A light machine gun is an air-cooled weapon, fed from a detachable box magazine or ammunition belt, that a single soldier can carry and operate. Modern light machine guns generally fire intermediate rifle ammunition, such as the 5.56×45mm NATO cartridge. However, there are several notable exceptions, such as the Bren gun and Browning Automatic Rifle, used in WWII, which fire full-power rifle cartridges (i.e., the .303 British and .30-06, respectively).
M249 SAW Light Machine Gun
Modern examples of light machine guns include the FN Minimi/M249 SAW (Squad Automatic Weapon) and the L86 LSW (Light Support Weapon).
Medium and General-Purpose Machine Guns (MMG/GPMG)
Medium machine guns are air-cooled, belt-fed, crew-served weapons that fire full-power rifle cartridges (e.g., 7.62×51mm NATO). The medium designation reflects both the caliber and the weight of the weapon system. An infantryman can typically transport a medium machine gun, but these weapons may require additional personnel to operate efficiently.
General-purpose machine guns are typically medium machine guns that foot soldiers can adapt to different roles and attach to various mounting systems. However, if the infantryman needs to carry and fire the weapon as an individual, they can.
MG-42 General Purpose Machine Gun
While the M1919 is designated a medium machine gun, the MG 42, M60, PK/PKM, and M240 are examples of GPMGs.
Heavy Machine Guns (HMG)
A heavy machine gun is an air- or water-cooled, belt-fed, fully automatic weapon. The designation of heavy may refer to either its weight or its caliber. For example, the Browning M1917, with its water cooling jacket, is considered a heavy machine gun, even though it fires the same .30-06 cartridge as the medium M1919.
Browning M1919 Heavy Machine Gun (image source: Wikipedia)
On the other hand, the Browning M2, chambered in .50 BMG (12.7×99mm NATO), is a heavy machine gun due to the power of its ammunition. The more powerful ammunition allows this type of HMG to effectively engage lightly armored vehicles, penetrate buildings and fortifications, and disable low-flying aircraft. HMGs are generally mounted on vehicles.
Full Auto vs. Semi Auto
In a semi-automatic or self-loading firearm, pressing the trigger fires a single round of ammunition and completes the cycle of operation. If you want to fire another shot, you have to release the trigger, allowing it to reset, and press it a second time.
When you press the trigger on a machine gun, the weapon will fire continuously until you release the trigger or the ammunition supply is exhausted. Machine guns are regulated under the National Firearms Act of 1934, the Gun Control Act of 1968, and the Firearm Owners’ Protection Act of 1986.
How Does a Machine Gun Work?
To understand how machine guns work, you should first familiarize yourself with the cycle of operation in self-loading firearms. The cycle of operation consists of the following eight functions:
Feeding is the act of placing a cartridge in the firing chamber of the barrel. The bolt or breechblock strips a round from the magazine in magazine-fed firearms and feeds it forward into the chamber.
However, the bolt will either withdraw the cartridge from the belt and insert it into the chamber or force it through the belt in belt-fed weapons. The machine gun will also typically use a camming system to advance the belt one position per shot.
The act of seating the cartridge fully in the chamber. This may be combined with feeding; however, when a cartridge is chambered, its forward movement stops on the headspacing point. This may be a point on the shoulder or rim, depending on the cartridge.
Locking is the act of securing the bolt to the barrel or receiver to contain the high-pressure expanding gases from cartridge ignition.
Firing is the act of releasing the hammer or striker to detonate the primer, igniting the propellant charge in the cartridge, and firing the round. Although machine guns often have separate firing pins, submachine guns that fire from the open-bolt position (e.g., the UZI) use a fixed firing pin machined into the face of the bolt.
When the pressure in the chamber has dropped to a safe level, the next function is unlocking.
Extracting is the act of withdrawing the cartridge from the chamber.
Ejecting is the act of expelling the spent cartridge casing from the weapon, usually through a port in the receiver. Machine guns that use disintegrating belts also have a separate port for ejecting the links.
As the action is driven rearward by bolt thrust or gas pressure, it cocks the hammer, preparing it for successive firing.
Ammunition Feeding Systems
While some machine guns are fed from detachable box or drum magazines, many are fed from belts. Modern ammunition belts consist of metallic links held together by cartridges and disintegrate during the firing cycle, keeping weight and bulk to a minimum.
Machine Pistols and Submachine Guns
Machine pistols are handgun-size, magazine-fed firearms capable of fully automatic or burst fire. Many machine pistols are derived from existing semi-automatic handguns, such as the Glock 18 and Beretta 93R.
Glock 18 Automatic Pistol
Others, such as the Soviet Stechkin APS, were explicitly designed to meet the self-defense needs of artillery and tank crews operating in confined spaces.
Submachine Guns (SMG)
Submachine guns are compact, fully automatic carbines designed to fire pistol cartridges. Well-known examples include the Heckler & Koch MP5, IMI UZI, and Ingram M10 (MAC-10).
Heckler & Kock MP5K SMG
The 9mm Luger (9×19mm) cartridge is the dominant submachine-gun caliber in the West, although .45 ACP is still used in the United States.
Find the Right Holster for Your Gun
At We the People Holsters, we’re passionate about the history of firearms and how they work, including machine guns. From the Maxim gun to the M60, M249, and M240, machine guns play a critical role in military firepower.
However, for the private citizen interested in concealed and open carry, semi-automatic handguns are more practical. When you need a high-quality Kydex holster for your self-defense firearm, we offer the best on the market for either inside- or outside-the-waistband carry.