Medium Machine Guns - II

In our last post, we looked at the early beginnings of medium machine guns. We will continue to study this class of machine gun in this post.

Before World War II, the German military came to the conclusion that static warfare tactics from World War I were obsolete and began to train using maneuver warfare concepts. Therefore, they needed a machine gun that could have a high rate of fire, but could be transported reasonably easily by hand, as well as used from a mobile platform. It was decided to design an air-cooled weapon with interchangeable barrels, so that it could fire rapidly for longer periods. The result was the MG 34 machine gun.

MG 34 Machine Gun. Click on the image to enlarge. Public domain image.

The MG 34 was used with great success by the German military in the early stages of World War II, but the rate of manufacture was slow because it needed some very precise machining to make it. Therefore, the German military held a new design contest for an improved machine gun and the result was the MG 42 machine gun.

Interestingly, the winning design was submitted by a company with no previous experience in firearms manufacturing, but they had experience in mass production technologies and knew how to produce stamped machine parts (they made metal lanterns!) The lead designer, Dr. Werner Gruner, actually attended a military machine gunner's course to familiarize himself with machine guns and talked to soldiers about what they wanted to see in a weapon. The resulting MG 42 design was much easier and faster to produce than the MG 34. It also had a much higher rate of fire (1200 to 1500 rounds/minute) than any other machine gun of that era. 

MG 42 on a tripod. Click on the image to enlarge. Public domain image.

Like the MG 34, the MG 42 could be carried by a single user and operated with a bipod in a light machine gun role. It could also be mounted on a tripod (such as in the image above) and used by a team in a medium machine gun role. When used in a medium machine gun role, the optimum team size was six: a commander who directed the team, a no. 1 gunner who carried the gun and fired it, a no. 2 gunner to carry the tripod (which weighed about twice as much as the gun!) and three others to carry spare barrels, ammunition, entrenching tools etc. The first three team members also carried pistols for protection, while the other three carried rifles. Often, the team consisted of only three members though, a gunner, loader and spotter.

The MG 42 was a very influential design and some variants continue to be used by military forces even in the present day. It also influenced other designs, such as the US M60 machine gun, the German MG 3 etc.

In our next couple of posts, we will study how the medium machine gun transitioned into the General Purpose Machine Gun class and the development of Squad Automatic Weapons (SAW)

Medium Machine Guns - I

In our last few posts, we looked at light machine guns and heavy machine guns. Briefly, a light machine gun fires intermediate-sized ammunition, comes with a bipod, operated by a single user and is generally carried by and used to support infantry. A heavy machine gun fires larger-than-ordinary rifle cartridges, is mounted on a vehicle or a tripod, sometimes operated by a team of people and is used against troops, light armor, buildings, low flying aircraft etc. In today's post, we will study another class of machine guns, the medium machine gun, otherwise called the MMG.

A medium machine gun is a weapon that fires full-sized rifle cartridges in automatic mode. They are generally air-cooled and belt fed. They also weigh somewhere in between the weight of a light machine gun and a heavy machine gun. Typical weight for a MMG is somewhere between 25 lbs. and 40 lbs. (or 11.34 kg. to 18.14 kg.) They began to emerge towards the end of World War I, as a balance between light machine guns and heavy machine guns. Recall that in World War I, light machine guns were made to be fed by smaller box magazines and fired in bursts only. Medium machine guns were designed to be fired on automatic for much longer, but without the heavy water cooling mechanism, weight or recoil of a heavy machine gun. Therefore, a medium machine gun offered flexibility to be used with a bipod by infantry like a light machine gun, or mounted on a heavier tripod or vehicle and used similar to a heavy machine gun. For this reason, a medium machine gun is sometimes referred to as "General Purpose Machine Gun (GPMG)" or "Universal Machine Gun".

The first real MMG was the Browning designed M1919 medium machine gun. This is a weapon that fires .30 caliber rifle cartridges from an ammunition belt. It was designed as an air-cooled variant of the M1917 heavy machine gun. Unlike the M1917 which weighs 103 lb. (47 kg.), the M1919 only weighs 31 lbs. (14 kg.) The minimum number of people needed to operate it is two, but sometimes upto four people were involved: a gunner (who fired the gun and also carried the tripod and some ammunition, when moving the gun), an assistant gunner (who fed the ammunition and carried the gun, when on the move) and two other people to carry extra ammunition, barrels, tools etc.

US Marines operating a M1919 A4 during World War II. Click on the image to enlarge. Public domain image.

This weapon was heavily used in World War II by different branches of the US military. It was used by infantry troops, mounted on jeeps, tanks, armored personnel carriers, aircraft etc. and continued to be used well into the Vietnam era. It was also used by other military forces around the world and modified to take other rifle cartridge calibers as well, such as .30-06, 7.62x51 NATO, .303 British, 7.62x54 mmR etc. In fact, it is still in use in some parts of the world.

In our next post, we will look at some more medium machine guns.

Machine Guns - General

In our last few posts, we studied different feed systems such as ammunition belts, chain feeds and feed strips. All these mechanisms are generally used with machine guns. Therefore, in the next series of posts, we will study all about machine guns.

A machine gun is a firearm that is capable of fully automatic fire. What this means is that as long as the firearm has ammunition available to it and the trigger is pulled, it will continue to load and fire ammunition automatically. Machine guns are capable of firing at high rates of several hundred rounds per minute and are designed to keep firing for considerable periods of time. The capability of maintaining sustained fire for long periods of time is what distinguishes a machine gun from an automatic rifle or an assault rifle (both of which can fire on full-auto only for limited periods of time).

US military doctrine has another interesting way of classifying automatic rifles versus machine guns. If the fully automatic firearm is operated by a crew, then it is a machine gun, but if a fully automatic firearm is operated by a single person, then it is an automatic rifle. In many cases, weapons fall exclusively into one of these two designations, however, we have one major oddball that falls into both categories -- the M249. US Army Field Manual FM 3-22.68 ("Crew-Served Machine Guns") describes the M249 as both an automatic rifle and a machine gun! Quoting from the manual chapter 4, section 5, paragraph 4-207, "Both the M249 automatic rifle and the M249 machine gun are identical, but its employment is different. The M249 automatic rifle is operated by an automatic rifleman, but its ammunition may be carried by other Soldiers within the squad or unit. The M249 machine gun is a crew-served weapon."

Machine guns can be portable as well as mounted and therefore, they are generally classified based upon size.

Before we dig deep into the topic, let us talk about submachine guns, which are portable firearms that are designed to fire pistol-sized ammunition. While they have a high rate of fire, some authorities do not consider these as "true machine guns" as they are not capable of sustained fire for long periods of time. Examples of these would be the Thompson submachine gun (which actually coined the term "submachine gun") also known as the Tommy gun, Chicago typewriter, Trench broom etc., Heckler & Koch MP5, Uzi etc. All these weapons are designed to fire pistol sized ammunition such as .45 ACP, 9 mm Parabellum etc.

Next, we have true machine guns like the Light machine gun, Medium machine gun, Heavy machine gun, General purpose machine gun which all use larger ammunition calibers (rifle calibers or larger). These weapons are generally heavier than other automatic weapons (even the "light" machine gun is heavier than an assault rifle, for instance). Examples of these would be the Lewis gun, the Bren gun, MG-34, Browning M1917, Browning M2, M60 etc.

A Lewis gun. Click on the image to enlarge. Public domain image. 

A M60 machine gun. Click on the image to enlarge. Public domain image.

We will study more into these various types of machine guns in the following posts.

Finally, we have weapons in the autocannon category. The difference between an autocannon and a machine gun has largely to do with the type and size of ammunition. If the firearm uses ammunition greater than 16 mm. diameter, or if it uses large caliber explosive rounds, then it is considered an autocannon rather than a machine gun. Examples of an autocannons include the M242 Bushmaster (which we studied briefly, when recently studying about chain guns), Oerlikon 20 mm. autocannon etc.

Since machine guns are designed to fire on automatic for longer periods of time, they tend to overheat quickly. Hence, many of them are either designed to have a built in barrel cooling system or feature a quick-change barrel replacement system. For the same reason, most machine guns are also designed to fire from an open-bolt, so that the breech area can be more efficiently air-cooled when the gun is not firing.

In the next few posts, we will study all about various types of machine guns and their history.