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The M249 is a light machine gun manufactured by FN. The design of the M249 was developed from the FN Minimi series design. The M249 has been seen used extensively by the United States Armed Forces and has been used in several conflicts including the Invasion of Panama, the Gulf War, the Bosnian War, the Kosovo War, the Afghanistan War and the Iraq War to replace the M16A1 rifle in the automatic rifleman role.

Design details

The M249 is a gas-operated, air-cooled, belt-and-magazine-fed, shoulder-fired automatic weapon. It feeds from either a 100-round or 200-round ammunition box, each round linked by a split-link disintegrating belt. It can also use AR-15 STANAG magazines; however, this is not advisable, as the weapon will exhibit frequent failure to feed malfunctions.

The M249 has a manual safety located on the trigger housing. When the safety is activated (no red ring showing), the weapon is safe - the bolt cannot be released. When the safety is deactivated (red ring showing), the weapon can be fired.

The M249 has a gas regulator for rate of fire, and can be set to either 750 rounds per minute (RPM) or 1000 RPM.

Like most machine guns, the barrel can be swapped out quickly. The M249 often features a bipod. [3]


The M249 has a hooded and semi-tied front sight. The rear sight assembly mounts on the top of the cover and feed mechanism assembly, and is adjustable from 300 meters to 1000 meters. Range changes are made on the rear sight by rotating the elevation knob to the desired range setting.

Rotation of the rear sight aperture is used for fine changes in elevation or range adjustments, such as during zeroing. One click of the rear sight for elevation or windage represents a half mil change, or .5 centimeters at 10 meters.


In the mid 1960's the US Army's primary armaments during early deployment in Vietnam included the M16 rifle for infantryman, the M60 machine gun for support and the M2 machine gun. The M2, though powerful; was very heavy and unwieldy to hoist in the jungle. The M60 was long and unwieldy in jungle fighting and typically both weapons required two man crews. The "Automatic rifle" concept was deemed obsolete; however use of the M16 in Vietnam, automatic fire consumed ammunition too readily. The Phase out of the BAR and M14 left no substantial single man firepower. The Army decided a single man portable machine gun with firepower and lighter weight. Experiments with the Stoner 63 which was used however it's complexity and high maintenance requirements left it only in the Hands of the Special Forces community.

By the late 60's the Army began a small arms program for a light machine gun, the program by the 70s the US Army designated specs for a 6mm cartridge weapon (but the logistics for an additional ammo to field rendered it mute) Trials began and the Belgian maker FN Herstal submitted prototype of it's Minimi machine gun; the Prototype XM249 was decided upon and in 1982 the designation M249 was selected.


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This was the first M249. This variant was made of steel with a side folding stock, similar to the FN MINIMI.


This variant is an upgraded version of the M249E1; the use of a PIP(Product Improvement Program) kit allowed the M249E2 to be more lightweight, due to the fact that some upgraded parts were plastic. This variant is used in the US military. Because the gun is an upgraded M249E1, it is usually referred to as M249.


The M249E3 has all the same features of the M249E2. This variant is also used in the US military. The M249E3 features a collapsible buttstock instead of the solid buttstock on the M249E2. It also features a shorter barrel for airborne, armored infantry, and CQC (Close Quarters Combat). When the stock is collapsed, it is 10inches shorter than the M249E2, it is usually referred to as M249 PARA.


A lightweight shorter version of the M249 designed to meet USSOCOM requirements.

Mk 46

This is a variant of the special purpose weapon adopted by USSOCOM. The program, which led to both the Mk 46 and Mk 48, was headed by the US Naval Special Warfare Command (NAVSPECWAR). Like the SPW, the carrying handle, magazine insertion well, and vehicle mounting lugs have been removed to save weight. However, the Mk 46 retains the standard M249 plastic buttstock instead of the collapsible buttstock used on the SPW. The Picatinny rail forearm also differs slightly from the SPW. The Mk 46 has the option of using the lighter SPW barrel or a thicker, fluted barrel of the same length. The Mod 0 variant has been discontinued in favor of the Mod 1.[4]

Mk 48 Mod 0

This is a 7.62x51 mm NATO version of the Mk 46, used by USSOCOM, when a heavier cartridge is required. It is officially classified as an LWMG (Light Weight Machine Gun) and was developed as a replacement for the Mk 43 Mod 0/1.

A request was put in for a new machine gun in 2001, and FN responded with a scaled up version of the M249 weighing in at ~18.5lb with an OAL of ~39.5". The new design achieved much better reliability than the M60-based weapons while bettering its light weight and maintaining the same manual of arms as the already in-use M249. USSOCOM was slated to begin receiving deliveries of the new gun in August 2003. Along with the Mk 46 Mod 0, the Mod 0 has been discontinued in favor of the Mod 1.[5]


This is the semi-automatic variant of the M249 LMG for civilian sale as a "Collectors item". It is visually identical to the M249 and can either fire from a belt or a magazine. However the gun has been modified to forbid the augmentation for automatic fire namely the bolt, the weapons internals also have welded and filled in portions to prevent the installation of Auto sears. Barrels can be swapped out just as they can be on the original M249. Instead of firing from an open bolt, however, the M249S fires from a closed bolt.[6]

See Also

  • Squad Assault Weapon trials


  1. Field Manual 23-14, Squad Automatic Weapon, M249; Pg 10, Table 1-2
  2. Field Manual 23-14, Squad Automatic Weapon, M249; Pg 6, section 1-2
  3. Field Manual 23-14, Squad Automatic Weapon, M249; Pg 6, section 1-2
  4. FN page, Mk 46 Mod 1
  5. FN page, Mk 48 Mod 1
  6. FN page on M249S

External links