The
heavy machine gun or
HMG is a larger class of
machine gun generally recognized to refer to two separate stages of machine gun development. The term was originally used to refer to the early generation of machine guns which came into widespread use in
World War I. These fired the standard (~
.30 or
7.62mm) rifle cartridge but featured heavy construction, elaborate mountings, and water cooling mechanisms that enabled heavy and sustained defensive fire with excellent accuracy, but with the cost of being too cumbersome to move quickly. Thus, in this sense, the "heavy" aspect of the weapon referred to the weapon's bulk and ability to sustain fire, not the cartridge caliber. This class of weapons is best exemplified by the
Maxim gun, invented by American
Hiram Maxim. The Maxim was the most ubiquitous machine gun of World War I, regional variants of which were fielded simultaneously by three separate warring nations (Germany with the
MG08 in
8mm Mauser, Britain with the
Vickers in
.303 British, and Russia with the
Pulemyot M1910in
7.62x54R).
The more modern definition refers to a class of large-caliber (generally ~
.50 or
12.7mm) machine guns pioneered by
John Moses Browning with the
M2 machine gun and designed to provide an increased degree of range, penetration and destructive power against vehicles, buildings, aircraft and light fortifications over the standard rifle calibers used in
medium or
general purpose machine guns. In this sense, the "heavy" aspect of the weapon refers to its superior power and range over light and medium caliber weapons. This class came into widespread use during
World War II, when the M2 was used widely in fortifications, on vehicles and in the air by the American forces. A similar HMG capacity was fielded by the Soviets in the form of the
DShK in
12.7x108mm. The ubiquitous German
MG42, though well suited against infantry, lacked the M2's anti-fortification and anti-vehicle capability, a fact that was noted and lamented by the Germans after the D-Day invasion. The continued need for a longer range machine gun with
anti-materiel capability to bridge the gap between exclusively anti-infantry weapons and exclusively anti-materiel weapons has led to the widespread adoption and modernization of the class; the M2 is now the oldest serving weapon in the US arsenal, and most nations are equipped with some type of HMG.
Currently, firearms with calibers smaller than 12 mm are generally considered medium machine guns, while those larger than 13–15 mm are generally thought of as
autocannons instead of heavy machine guns.
[edit]History
In the late 19th century,
Gatlings, and some other externally powered types such as the
Nordenfelt were often made in range of calibers, such as half inch and one inch. Thanks to their many barrels, overheating was not so much of issue, and they were also quite heavy.
When
Hiram Maxim developed his recoil-powered machine gun that used a single barrel, the first main design was a modest 26 pounds (11.8 kg) and fired a .45-inch rifle-caliber bullet (from a 24-inch barrel). As a famous photo of Maxim himself will attest that even he could pick it up by its 15-pound tripod (6.8 kg) with one arm. It was similar to present-day medium machine guns, but it could not be fired for extended periods. As a result, he created a water jacket cooling system to enable it to fire for extended periods. This added significant weight, as did the change to more powerful cartridges.
There were two main heavy, rapid-fire weapons, the heavy-caliber, manually powered machine guns and the water-cooled Maxim types. Soon, by the end of the 19th century, many new designs were developed, some powered by gas or recoil or some combination of the two (Colt 1895, Hotchkiss, etc.). Also, rather than the rather heavy water jacket, new designs introduced other types of cooling, such as barrel replacement, metal fins, or heat sinks or some combination of them.
[edit]Various designs
Machine guns diverged into heavier and lighter design. The later model water-cooled
Maxim guns and its derivatives the
MG 08 and the
Vickers gun, as well as the American
M1917 Browning machine gun, were all substantial weapons. The
.303 Vickers, for example, weighed 33 lb (15 kg) and was mounted on a tripod that brought the total weight to 50 lb (23 kg). The heavier designs could, and in some cases did, literally fire for days on end. The need was to be able to cut down potentially thousands of charging soldiers. The heavy machine gun was mounted on a tripod and was water cooled, and a well-trained and well-supplied crew could fire for hours on end. Carefully positioned heavy machine guns could stop an attacking force before they reached their objectives.
[edit]Light machine guns
However, during the same period a number of new, lighter air-cooled designs were developed that rather than weighing well over 30 lb (15 kg) were lighter and mobile. In
World War I they were to be as important as the heavier designs, and were used to support
squads and
infantry on the move, on aircraft, and on many types of vehicle as well (and on tanks to some extent). The two that would become critical were new medium and light machine guns. The new medium machine guns offered less, or more difficult to use, cooling than the heavier designs, but more than the lightest.
The lightest of the new designs were not capable of sustained fire, as they did not have an extra cooling features and were fed from a comparatively small magazine. Essentially a machine rifle with a
bipod, weapons like the
Chauchat or the
Madsen 1902 were the most mobile, but were made for single and burst fire. These were used in assaults to great effect by infantry, but were not as popular on other mounts.
[edit]Medium models
The medium designs offered greater flexibility, either using a
bipod and being used like lighter designs, or being put on a
tripod or on heavier mounts. The
Hotchkiss Mark I (e.g., Benet-Mercie, M1909) was a 27.6 lb (12.2 kg) machine gun that normally used a mini-tripod and linkable 30-round strips, but there was also a
belt-fed version of it. Not to be confused with heavier Hotchkiss models (such as the
M1914), the design proved a useful intermediate and would serve even to the end of
WWII in some roles. The design would be followed by lighter machine guns and better medium types.
[edit]Lewis gun
The
Lewis gun, which weighed 27 lb (12.3 kg), was commonly used with a 47-round
drum and
bipod; it was used while moving to support
squads, and on vehicles and aircraft as well, or on a tripod (either for
anti-aircraft use, or to fill in for a heavier machine gun). What made it very useful was that it was significantly lighter than water-cooled weapons, but could fire nearly as much due to a very large cooling assembly. This sort of multipurpose machine gun would be further developed, and later given names like Universal Machine gun (later called the
general-purpose machine gun) and would eventually supplant the water-cooled designs. Later designs have mostly switched to fast barrel replacement for cooling, which further reduces the weapon's weight (but can increase the total weight carried by a soldier). Some earlier designs like the
Vickers had this feature, but it was mainly for barrel wear, not for cooling (as they normally used water cooling). It was in the 1920s and 1930s that fast barrel replacement for cooling became more popular (such as the
ZB 1930, and later the
MG34 and the
Bren).
XM312 .50 cal machine gun
[edit]Heavier models
The heavier water-cooled designs continued to be used throughout WWII and into the 1960s, but were gradually phased out in favor of air-cooled designs. The mediums are now used both as heavy machine guns while mounted on
tripods and as
light machine guns while mounted on
bipods. This was possible in part because a heavy, static MG position was not a very effective tactic in vehicle-centered warfare, and the lighter air-cooled designs could nearly match the capabilities of water-cooled designs with a combination of other lighter cooling features. Also, during WWII, many new larger-caliber machine guns were developed, the Soviet Union having developed a number of larger calibers, as well as other countries. (There was the large-caliber Vickers design, for example.)
[edit]Latest inventions
By the latter half of the 20th century, use of heavy machine guns, especially water-cooled designs, was declining. The venerable
Browning M1917 saw its last major use during the 1960s in the
Vietnam conflict. At the same time, however,
Gatling-type weapons were making a comeback. Those firing
7.62 mm such as the
General Electric Minigun were popular for ships, and helicopter mounted weapons, and have established a niche; the
Soviet Unionalso developed a number of
Gatling-type weapons. The need for sustained fire on the ground, however, was now nearly entirely the domain of air-cooled
medium machine guns that used some cooling manifolds, barrel replacement, and special or heavier barrels. Since there were no more rifle-caliber machine guns (aside from the Gatlings), the term heavy machine gun now mainly just refers to heavy-caliber machine guns. By the 21st century, new heavy-caliber machine guns have become much lighter (for a given type) as well; less than many of the old water-jacketed type
5 heavy machine gun (PR China)
W85 heavy machine gun on universal mount
Chinese soldiers aim with the W85 heavy machine gun
Caliber: 12,7x108
Weight: 18,5 (gun) + 17,5 (tripod)
Length: mm
Length of barrel: mm
Feeding: belt
Rate of fire: 550-600 rounds/min
The W-85 heavy machine gun at the first glance looks much like the Type 77 heavy machine gun, but closer examination reveals certain differences, such as very thick gas tube below the barrel (which conceals a conventional gas piston, as opposed to piston-less system of the Type 77 and Type 85), and the receiver is of generally rectangular cross-section, while the receivers of the Type 77 and Type 85 are more or less of tubular design. It is believed that the W-85 was built in parallel with the Type 85 HMG, most probably on a competitive basis, but lost in the PLA trials. Apparently, it survived as a commercial venture, as available information suggests that the NORINCO Corporation sold for export at least some armored vehicles armed with a “W-85 12.5mm machine gun”. Recently, information has surfaced in Chinese publications about the “new” 12.7mm QJC 88 tank machine gun, which looks exactly like the tank version of W-85.
The W-85 heavy machine gun is a gas operated, air cooled, belt-fed, automatic only weapon. Its design is loosely based on the Soviet DShKM / Chinese Type 54 heavy machine gun, although there are many differences in various subsystems.
The W-85 uses a long-stroke gas piston, located below the barrel. The piston is rigidly attached to the bolt carrier, which carries a compact breech block (bolt). The locking system can be described as an “inverted” Degtyarov / Kjellman flap lock; it uses two pivoting flaps, one at either side of the bolt, to engage cuts in the receiver walls. The key difference between the W-85 and DShKM is that, in the W-85, the flaps are pivoted at the rear and have special locking projections that lock into the receiver walls.
The feed is also broadly based on that of the DShKM, and the feed module is a detachable unit, attached to the top of the receiver. It is operated by a swinging arm which projects down at the right side of the feed. The fork-shaped bottom end of the arm engages a reciprocating charging handle, which is attached to the bolt carrier. Feed is from the left side.
The gun fires from an open bolt, in automatic mode only. The firing pin is operated by a projection on the bolt carrier; the same projection forces the locking lugs outwards so the gun cannot fire unless the bolt is fully locked. A manual trigger is fitted to the rear of the receiver, and dual spade grips provide firing controls. W-85 can be installed either on universal tripod, or on vehicle (tank) mounts.
-- tHE BEST PART OF THE WAR IS THE INVENTION OF HEAVY MACHINE GUN
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