M240 machine gun
The M240 machine gun, officially the Machine Gun, 7.62 mm, M240, is the U.S. military designation for the FN MAG, a family of belt-fed, gas-operated medium machine guns that chamber the 7.62×51mm NATO cartridge.
The M240 has been used by the United States Armed Forces since the late 1970s. It is used extensively by infantry, most often in rifle companies, as well as on ground vehicles, watercraft and aircraft. Though it is heavier than some comparable weapons, it is highly regarded for reliability and its standardization among NATO members is a major advantage.
All variants are fed from disintegrating belts and are capable of firing most types of 7.62 NATO ammunition. M240 variants can be converted to use non-disintegrating belts. There are significant differences in weight and some features among some versions which restrict the interchangeability of parts. The M240s used by the U.S. military are currently manufactured by U.S. Ordnance in Reno, NV as well as FN America, the American subsidiary of the Belgian company FN Herstal.
The M240B and M240G are usually fired from integrated bipods, tripods, or vehicular mounts; regarding tripod use, the U.S. Army primarily uses the M192 lightweight ground mount, while the U.S. Marine Corps uses the M122A1 tripod, a slightly updated M2 tripod.
History
Development
Manufactured by the American division of the Belgian company Fabrique Nationale d'Herstal, the FN MAG was chosen by the U.S. military for different roles after large worldwide searches and competitions. The MAG is a belt-fed, gas-operated, air-cooled, crew-served, general-purpose machine gun. Its versatility is demonstrated by its ability to be fired effectively from its integral bipod, mounted on a tripod, on ground vehicles, watercraft and aircraft.It was first adopted by the U.S. Army in 1977, as a coaxial tank gun, and slowly adopted for more applications in the 1980s and 1990s. The M240 and M240E1 were adopted for use on vehicles. This led to further adoption in more uses, especially for the Army and Marine Corps infantry.
While possessing many of the same basic characteristics as its predecessor, the durability of the MAG system results in superior reliability when compared to the M60. The MAG actually has a more complex gas system than the M60, but gives better reliability combined with lower maintenance requirements, though this comes at greater manufacturing cost and weight.
Compared to other machine guns, its rating of 26,000 mean rounds between failure is quite high for its weight – in the 1970s when it was first adopted it achieved about 7,000 MRBF. It is not as reliable as some very heavy older designs, but it is quite reliable for its mass.
Testing and adoption
The U.S. adoption of the MAG has its origins in the late 1960s and early 1970s as a project to procure a new coaxially mounted 7.62 mm machine gun for tanks to replace the M73 and M219 machine guns then being used. The 1950s-era M73 had been rather troublesome, and the derivative M73E1/M219 was not much of an improvement. A number of designs of the period from various countries were considered; the final two candidates were the M60E2 and the FN MAG, which underwent comprehensive testing alongside the older M219 for comparison.Two main criteria analyzed were "mean rounds between stoppages" and "mean rounds between failures". The results for the evaluated machine guns were the following:
| Type | Rounds fired | MRBS | MRBF |
| FN MAG 58 | 50,000 | 2,962 | 6,442 |
| M60E2 | 50,000 | 846 | 1,669 |
| M219 | 19,000 | 215 | 1,090 |
| Minimum specified | 850 | 2,675 | |
| Minimum desired | 1,750 | 5,500 |
File:M1A1 Abrams gunner’s primary sight.jpg|thumb|M240 coaxial machine gun aboard an M1 Abrams tank
The MAG itself underwent some improvements and the M60E2 was a specialized coaxial variant that differed from some of the other types. The qualities of the M60 variants vary considerably, such as between the M60E4 and the M60C. The clear winner was the MAG, which was designated as the M240 in 1977 after the army competition.
The M240 was adopted as the U.S. Army's standard vehicle machine gun in 1977. The Marine Corps also adopted the M240 and M240E1 for use on vehicles like the LAV-25. It then went on to replace many older types of vehicle machine guns in the 1980s. U.S. Navy SEALs continued to use the "CAR-60" version of the M60 machine gun due to its lighter weight and slower rate of fire, which allows a more effective duration of fire with allowable levels of ammunition carried.
The M240 proved popular enough that it was adapted by the infantry later on, as the M240G and M240B. The USMC adopted the M240G for this role in 1991, where it not only replaced the original M60s used by the Marine Corps infantry, but also the upgraded M60E3 that the Marines had started using in the 1980s. In the late 1990s, the Army adopted the M240B for the infantry role – they had considered the M60E4, which did not offer commonality with the vehicle-borne M240, other FN MAG users within NATO, or the USMC.
The various versions of the M240 have not entirely replaced all the M60 versions, though they have for most main applications and roles. The M60 is still, in some cases, used by the Navy.
2022 military solicitation
As of March 2022, the United States Army had a solicitation ongoing for a M240 machine gun 6.8×51mm conversion kit to modify the 7.62×51mm NATO-chambered M240B and M240L general-purpose machine guns to fire the 6.8×51mm ammunition.Design details
The weapon fires from the open bolt position, meaning that the bolt is held to the rear and only moves forward as it is firing a round. The firing pin is static and the bolt moves around the firing pin, circumventing any need for a hammer. A sear is used to time the internal mechanisms of the weapon to provide a consistent rate of fire, ensuring proper function and accuracy.The rate of fire may be controlled by three different gas regulator settings. The first setting allows the weapon to cycle at 650–750 rounds per minute, the second setting being 750–850 rounds per minute, and the third setting being 850–950 rounds per minute. These settings are changed by dismounting the barrel, removing the gas regulator collar and turning the gas regulator to allow more or less gas to move through the weapon system. It is generally performed only when necessary to return the gun to operation after fouling has caused sluggish operation and there is no time to properly clean the weapon.
The barrels can be exchanged rapidly, via a barrel release button located on the left side of the weapon. The weapon is cleared first and then the button is held down, while the barrel's carrying handle is moved from the right side of the weapon to the center, unlocking it from the receiver. At this point, the button is released and the barrel is then pulled free of the receiver and placed to the side. The new barrel is inserted into the receiver and then the carrying handle is shifted to the right, locking it into place.
During prolonged firing, the barrels can become hot enough to inflict second-degree burns instantly without becoming visibly different.
Variants
first introduced the MAG general-purpose machinegun in the early 1950s. The M240 is the US military's adoption of the FN MAG. Parts compatibly of other MAG variants adopted by other NATO members are interchangeable. This has significant advantages in training, logistics support, tactical versatility, and joint operations.M240
The M240 is adapted as a coaxial machine gun for tanks and 7.62 mm fire power on light armored vehicles. The M240 is part of the secondary armament on the U.S. Army M1 series Abrams tank, M2/M3 series Bradley Fighting Vehicle, and the U.S. Marine Corps LAV-25.The M240E1 is the U.S. Marine Corps version of the original M240 coaxial/pintle-mounted machine gun that is used on vehicles like the LAV-25. It can also be fitted with spade grips for flexible use, like the ones from the M240D.
The M240C is the right-hand variant on the original coaxial M240, it is identical to the M240 except for the ammunition cover and feed tray. It has a right-handed feed for use on the M2/M3 Bradley Fighting Vehicle and LAV as the coaxial machine gun. It is fed from the left on the M1 Abrams and other M1 variant tanks. The M240C uses a charging cable instead of a charging handle, has a cut-off pistol grip and has a special paddle assembly that allows the trigger to be actuated by means of a solenoid. Since the machine gun is not meant to be handled during use, the barrel is fully exposed and must be handled with asbestos mittens during barrel changes.
The rate of fire of the M240, M240E1, and M240C can be controlled by three different gas regulator settings;
- The first setting allows the weapon to have a cyclic rate of fire of around 650–750 rounds per minute,
- The second setting allows the weapon to have a cyclic rate of fire of around 750–850 rounds per minute,
- The third setting allows the weapon to have a cyclic rate of fire of around 850–950 rounds per minute.
M240D
The barrel assembly contains a three position gas regulator. The first setting allows the weapon to cycle at 650–750 rounds per minute, the second gas setting allows the weapon to cycle at 750–850 rounds per minute, and the third setting allows the weapon to cycle at 850–950 rounds per minute.
The aircraft configured M240D weighs 25.6 lb and is 42.3 in long, whilst the egress configuration weighs 26.2 lb and is 49 in long.