M240 / FN MAG

The M240 machine gun, officially designated Machine Gun, 7.62 mm, M240 by the U.S. military, is the American variant of the FN MAG, a series of belt-fed, gas-operated medium machine guns that fire the 7.62×51mm NATO cartridge. Developed by Fabrique Nationale d'Herstal in Belgium, the FN MAG was selected by the U.S. military after extensive testing in the late 1960s and early 1970s. Initial adoption occurred in 1977 for coaxial use on tanks, with broader application across various platforms expanding in the 1980s and 1990s. It was later adopted for infantry use by the U.S. Army and Marine Corps, partially replacing older M60 variants due to its superior reliability.

Operationally, the M240 is gas-operated and fires from an open bolt position. It features a static firing pin and a sear for rate control. The rate of fire can be adjusted via a three-position gas regulator, offering settings for approximately 650–750, 750–850, or 850–950 rounds per minute, depending on the variant. The weapon utilizes rapid barrel exchange capability, and ammunition is typically fed from disintegrating belts, although some variants can be converted to use non-disintegrating belts.

Numerous variants exist within the M240 family:

• The original M240, M240E1, and M240C are primarily configured as coaxial or pintle-mounted weapons, differing in feed direction (M240C is right-hand feed) or configuration features.

• The M240D is an upgrade of the M240E1 for aircraft use with egress capability.

• The M240H is a further improved M240D with rail features and faster egress conversion.

• The M240G is a ground configuration adopted by the USMC, adaptable for various roles.

• The M240N is a variant specific to watercraft.

• The M240B is a standard infantry version featuring a hydraulic buffer and a slower single rate of fire setting compared to the M240G.

• The M240L incorporates titanium components for significant weight reduction.

Other variants include the Barrett 240 series (240LW, 240LWS) utilizing alternative manufacturing methods and the Ohio Ordnance Works 240 variants (GPMG, P, SLR) offering select-fire or semi-automatic capabilities.

The M240 entered U.S. military service in 1977 as a vehicle-mounted weapon, replacing the troubled M73 and M219 machine guns. Its adoption expanded through the 1980s, leading to its use on vehicles like the M1 Abrams and M2/M3 Bradley. It was later adopted for infantry use, notably by the U.S. Marine Corps (M240G in 1991) and the U.S. Army (M240B in the late 1990s) after testing demonstrated superior reliability compared to the M60. Despite its prevalence, it has not completely replaced all M60 versions in U.S. service. As of 2022, the U.S. Army explored a 6.8×51mm conversion kit for M240 variants.

The M240 and its variants are used by numerous military forces globally. Identified government users include Argentina, Colombia, Croatia, Georgia, Indonesia, Iraq, Japan, Poland, Philippines, Romania, Spain, Syria, Turkey (license built), Ukraine, and the United States (Army, Marine Corps, Air Force Security Forces, Texas Highway Patrol, Los Angeles County Sheriff's Department, Long Beach Police Department). Non-state users like the Free Syrian Army have also been documented utilizing the weapon.