M60 7.62mm Machine Gun
The M60 was type standardized in 1957 and began to be replaced by variants of the M240 starting in the late 1970s. During that period, 4 major variants were developed, including the standard infantry type, as well as 3 minor variants. The M60 was developed for use as an infantry weapon, for use a fixed and flexible vehicle weapon, and for use on both fixed and rotary wing aircraft. After its replacement in broad service with the M240, another variant for special operations forces was developed.
The major variants of the M60 were those for infantry use (sometimes referred to as M60A), 2 variants for use by helicopter door gunners (M60B and M60D), and a remote firing weapon for fixed applications in helicopter armament subsystems (M60C). The M60B was short lived, though it lent some to the development of the M60C. The M60D was in turn modified from the M60C design.
Early on in the M60s life, a attempt to improve the basic functioning, and otherwise simply the design was undertaken. The result was the M60E1, the first minor variant, which sought to improve the ease of changing the weapon's barrel and reduce the number of parts in the weapon. The M60E1 has a modified barrel extension that was about l3 inches long. It was determined that each time a barrel was changed, the gas cylinder assembly, being quickly removed, could have been rapidly interchanged from one barrel to another. This was the basic approach of the M6OE1 machine gun. In the end, the improvements of the M60E2 were not adopted.
The second minor variant, the M60E2, offered an alternative to the M73, and later M219, fixed tank machine guns. The main features of the M60E2 machine gun are a gas exhaust system that collects the spent gas from around the gas cylinder group and directs it forward to the muzzle area and a barrel extension, which carries the muzzle gases forward, and away from the gunners' compartment. An obturating type gas cylinder nut and an auxiliary collar on the operating rod effectively restrict the gases from reaching the receiver area.
Other features of the M60E2 include the ability to convert a standard infantry M60 for tank installations by removing the forestock, buttstock, pistol grip, rear sight, and charging handle. These items are then replaced with an M60C type buttstock cover, a firing solenoid assembly with manual trigger, a mount adapter bracket, and a redesigned charging handle. The regular barrel assembly is replaced with an assembly which includes a barrel extension and gas evacuator system.
The M60E2 machine gun for tank use was basically an M60C model with a barrel extension and a gas evacuator system. It also incorporated a quick change barrel system similar to the employed on the M60E1. Performance of the modified gun was similar to the basic M60. A variant of the weapon, specifically for the US Army's Mechanized Infantry Combat Vehicle program was designated as the XM238.
The M60E3 and M60E4 were both attempts to improve the reliability and functioning of the basic M60 machine gun. The M60E3 featured a revised handguard and bipod arrangement, which also included a vertical forward grip. A short barrel was available for use by special operations forces. The M60E4 was a further product improvement of the weapon, seeking to improve issues of barrel life and overall reliability found on the M60E3. All major components of the new weapon were interchangeable with older infantry type M60s, which could themselves be readily converted to the new configuration. The barrel was stellite-lined to improve barrel life. A short barrel was again made available for special operations forces.
Though the US Army chose a variant of the M240 over the M60E4 in the 1990s as the next standard infantry weapon, the short barrel M60E4 configuration was selected a replacement for similar M60E3s in service with Naval Special Warfare units. These weapons were designated as Mk 43 Mod 0. A variant with additional MIL-STD-1913 accessory rails was designated as the Mk 43 Mod 1.
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