The M240, officially the Medium 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 machine guns, 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 (MRBF) 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" (MRBS, malfunctions that can be cleared within minutes) and "mean rounds between failures" (MRBF, such as a part breaking). 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
The FN MAG underwent several improvements, while 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 FN MAG, which was designated as the M240 in 1977 after the U.S. Army competition.
The M240 was adopted as the U.S. Army's standard coaxial machine gun for tanks and armored vehicles 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" (M60E3) 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 (though lighter and cheaper) 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 M240 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 machine gun 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 machine gun 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 machine gun 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 machine gun.
The barrels can be exchanged rapidly, via a barrel release button located on the left side of the machine gun. The machine gun is cleared first and then the button is held down, while the barrel's carrying handle is moved from the right side of the machine gun 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
FN Herstal first introduced the MAG general-purpose machine gun 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 (installed alongside the main machine gun) 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 (M1A1, M1A2, M1A2 SEP) 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 machine gun to have a cyclic rate of fire of around 650–750 rounds per minute, The second setting allows the machine gun to have a cyclic rate of fire of around 750–850 rounds per minute, The third setting allows the machine gun to have a cyclic rate of fire of around 850–950 rounds per minute.
M240B
The M240B (M240 Bravo), formerly designated as the M240E4 is the standard infantry medium machine gun of the U.S. Marine Corps. The U.S. Navy and Coast Guard likewise utilize the machine gun system, and is also still used by some units in the U.S. Army. It comes configured for ground combat with a buttstock and bipod, though it can also be mounted on tripod, ground vehicles, aircraft, aboard ships, and small boats.
The M60E4 (Mk 43 as designated by the Navy) was pitted against the M240E4 (former designation of the M240B) in the Army trials during the 1990s for a new infantry medium machine gun, in a competition to replace the decades-old M60s. The M240E4 won, and was then classified as the M240B. This led to 1,000 existing M240s being sent to FN for an overhaul and a special kit that modified them for use on ground (such as a stock, rail systems, etc.). This led to procurement contracts in the late 1990s for the all-new M240B. However, a new feature was added, a hydraulic buffer system to reduce the felt recoil as incorporated in the M60. While the M240B had been more reliable in the tests, it was a few pounds heavier than the M60E4, which led to the development of the lighter M240L. The Army M240 converted to the M240B configuration should not be confused with the large numbers of M240/E1 converted to the M240G configuration for the Marine Corps.
The main differences between the M240B and M240G is the Picatinny rail system, hydraulic buffer inside of the butt stock to reduce the amount of recoil felt by the gunner, and the number of gas settings on the gas regulator plug. The M240G has three gas settings, allowing the machine gun to have a fire rate between 650 and 750 rounds per minute when set to the first gas setting, 750–850 rounds per minute at the second gas setting, and 850–950 rounds per minute at the third gas setting, whereas the M240B only has one setting, restricting the fire rate to between 550 and 650 rounds per minute. The smaller gas port used on the M240B slows down the rate of fire, which increases the longevity of the machine gun by reducing stresses on the action. A side effect is a machine gun that will not fire when extremely dirty as the energy on the piston is reduced.