M249 light machine gun

M249 light machine gun
File:AF M249.jpg The M249 SAW
Type	Light machine gun
Place of origin	Belgium  United States
Service history
Used by	United States Armed Forces
Production history
Manufacturer	Fabrique Nationale de Herstal
Unit cost	US$4,087[1]
Variants	See Variants
Specifications
Mass	22 lb (10 kg)
Length	41 in (1041 mm)
Barrel length	20.5 in (521 mm)
Cartridge	5.56x45mm NATO
Action	Gas-operated, open bolt
Rate of fire	750-1000 rounds/min
Muzzle velocity	915 meters/sec
Effective firing range	1000 m
Feed system	M27 linked belt, STANAG magazine

The M249 squad automatic weapon, formally Squad Automatic Weapon, 5.56mm, M249 is an American version of the FN Minimi manufactured in the U.S. and used by all branches of the United States Armed Forces. The gun was introduced in 1984, being the only candidate to successfully pass tests. It provides the heavy volume of fire of a traditional machine gun with ammunition that weighs significantly less.

The M249 is gas-operated and air-cooled. It has a quick-change barrel so that an overheated or jammed barrel may be rapidly replaced by the gunner. A folding bipod is attached near the front of the gun, though fixed tripod is also issued to troops.

In 1965, the U.S. Army's primary machine guns were the M2 Browning and M60. The M2 was a large calibre heavy machine gun usually mounted on vehicles or in pre-prepared emplacements.^[2] The M60 was a more mobile medium machine gun intended to be carried with the troops to provide heavy automatic fire.^[3] Both were very heavy weapons and usually required a crew of at least two men to operate efficiently, meaning they were best employed at platoon level or higher.^[4] In addition, while the M16 rifle, the U.S. Army's standard issue assault rifle, had a fully automatic setting, army doctrine required troops to use its semi automatic mode on most occasions to increase accuracy and conserve ammunition. This left squad-sized units with little sustained fire support in combat situations.^[5]

It was decided that an individual machine gun lighter then the M60 firing 6 mm ammunition would be an advantage. Design proposals for the new gun were solicited in 1969. Designs were required to have a weight of less than 10 kg (22 pounds) with 200 rounds of ammunition and a range of at least 730 metres (800 yards). Weapons submitted for testing by manufacturers included the experimental Colt CMG-1, based on the M16, the Heckler & Koch HK23 and the Fabrique Nationale Minimi, an air-cooled, gas-operated weapon firing the same rounds as the M16. The Minimi proved the most effective and was accepted when the plans for new 6 mm bullets were scrapped due to the greater logistical burdens a new cartridge would entail.^[6][7]

The new gun entered U.S. Army service as the M249 squad automatic weapon in 1984, and was adopted by the U.S. Marines a year later. The M249 model is built in the U.S. and is slightly different from the regular Minimi; the butt and hand grips are a different shape, along with some minor internal modifications.^[8] One man in every 4-man fireteam—the automatic rifleman—was issued with the new weapon to provide automatic fire for his unit. In this regard, the M249 filled the void created by the retirement of the Browning Automatic Rifle in the 1950s^[1]

Reception was mixed: it fulfilled the light machine gun role well but was not as effective when fired from the shoulder.^[9] It was praised for its extreme durability and massive firepower, though a number of areas for improvement were highlighted: its attachment for firing blank ammunition did not fit properly, the bipod was very weak and broke easily, its sling attachment was awkward and its design incorporated many slots and gaps which tended to accumulate dirt and were hard to clean out.^[10] Some claimed that the heavy-barrel version of the M16 rifle was a more effective light machine gun.^[11] There were many complaints about jams when using magazines (many magazine springs could not keep up with the guns rate of fire) and the need to change the barrel regularly.^[12]

The M249 is fired from the open bolt position and is gas operated; expanding gases which occur during the firing of a bullet are used to push back a piston. This piston ejects the spent casing and chambers another cartridge, ready for firing. It has no purpose-built cooling system and is simply exposed to the air to cool after firing.^[8] To prevent overheating and jams the gun has a quick-change barrel; each gunner is issued with a spare. A folding bipod with adjustable legs is attached near the front of the weapon, though a fixed tripod is also available. The gun provides accurate fire approaching that of a rifle yet gives the heavy volume of fire common to a machine gun. It normally fires at 750 rounds per minute, though this can be increased to its maximum rate of fire of 1,000 rounds per minute if required, and a semi-automatic mode is also available.^[13]

The M249 fires 5.56x45mm NATO cartridges from M27 linked belts or STANAG magazines.^[13] Tactically, squad automatic weapons are either carried with a maneuvering unit and fired while handheld or positioned to provide covering fire for other units.^[4]

On April 2002, A "Lessons Learned in Afghanistan" report by LTC Charlie Dean and SFC Sam Newland of the U.S. Army Natick Soldier Center was released. The report found that 54% of SAW gunners had problems maintaining their weapons, and 30% reported the gun easily rusting. 80% of soldiers surveyed were pleased with the weapon’s accuracy and lethality, and most were confident in their weapon. Soldiers reported ammunition drums falling off and rattling.^[14]

On 15 May 2003, An "Operation Iraqi Freedom PEO Soldier Lessons Learned" report by LTC Jim Smith, U.S. Army, was published. It was generally positive of the M249, claiming that it "provided the requisite firepower at the squad level as intended". He also praised the SPW variant, saying "The short barrel and forward pistol grip allowed for very effective use of the SAW in urban terrain".^[15] At the National Defense Industrial Association 2007, Colonel Al Kelly of the 1st Battalion, 17th Infantry gave a presentation which said that the M249 had "good range, excellent reliability" and "excellent tracer". He also said that the cloth pouch preferred over plastic box for holding linked ammunition, and that "knock down power is poor but is compensated by rate of fire".^[16]

XM249E1

Experimental rifling; changes proved successful and were incorporated into the weapon

M249E2

Product improvement kit modifies the barrel, handguard, stock, pistol grip, buffer, and sights^[1]

M249E3 Para

The M249E3 Para is a compact version of the gun with a shorter barrel and sliding aluminum butt, so called because of its intended use with airborne troops.^[8]

M249E4 Special purpose weapon

A lightweight and shorter version of the weapon designed to meet USSOCOM requirements. The SPW has a detachable bipod and pistol grip.^[8]

Mk 46 Mod 0

Even lighter version than the SPW for use with USSOCOM. Carrying handle, magazine insertion well and vehicle mounting lugs all removed, and Picatinny rails added^[17]

Mk 48 Mod 0

A 7.62mm version of the Mk 46, also used by USSOCOM.^[18]

Many of the SAWs currently in U.S. Army and Marine Corps service are over 10 years old and becoming unreliable. While a refurbishing program has extended their lives, heavy use is taking its toll and their condition is slowly deteriorating. The Marine Corps are currently looking for a replacement for their M249s, and are now testing magazine-fed weapons from at least six gun makers. Among the designs being considered is the LWRC Infantry Automatic Rifle (IAR), a weapon resembling the M4 carbine and weighing less than 5.5 kg compared to the SAW's 10 kg. The Marines Corps plan to buy 4,100 IAR to complement and partially replace its 10,000 M249s.^[19]

The army, however, has ruled out the IAR. Colonel Robert Radcliff said "We are not considering adopting an auto rifle for the infantry squad" explaining "It’s really all about firepower. The Marine Corps has a 13-man squad; we have a nine-man squad—that’s a four-man difference". The army does, however, want to replace their aging guns with new ones, possibly the Mk 46 variant.^[20]