Thursday, September 25, 2008

M249 SAW


M249 SAW (Squad Atomatic Weapon)







Type:
Light machine gun
Place of origin:
Belgium United States

Production history:
Manufacturer:
FN Herstal, FN Manufacturing
Unit cost:
US$4,087
Specifications:
Weight:
16.5 lb (7.5 kg) empty15.95 lb. (7.25 kg) (Para model)
Length:
SAW:41 in (1041 mm)
Para: 36 in (914 mm) (stock extended), 30.5 in (775 mm)(stock compressed)
Barrel length:
M249: 20.5 in (521 mm), Para model: 14.5 in (368 mm)
Cartridge:
5.56x45mm NATO
Action:
Gas-operated, open bolt
Rate of fire:
750-850 rounds/min
Muzzle velocity:
915 meters/sec
Effective range:
1000 m
Feed system:
M27 disintegrating belts from 200-round plastic ammo box or 100/200-round reusable soft packs
Various STANAG Magazines.
The M249 Squad Automatic Weapon (M249 SAW) is the United States military designation for a sub-family of the FN Minimi squad automatic weapon (from Mini-mitrailleuse French: "mini-machine gun". Both are 5.56x45mm NATO light machine guns manufactured by Fabrique Nationale (FN) and its subsidiaries.
The Minimi is manufactured by Fabrique Nationale in Belgium, while the M249 is made by FNH USA, the American subsidiary of FN. The M249 was the winner of a competition carried out by the U.S. military in the late 1970s–early 1980s for a new squad automatic weapon. The Minimi has been adopted by many other countries since that time, especially among NATO members.
The M249 was one of many firearms fielded in the late 1970s, 1980s and 1990s that was part of the NATO adoption of a new smaller round. The Belgian cartridge (SS109), developed for use with the Minimi, was the winner of the competition for the new, standardized 5.56 mm round. In the United States, the M16A2 was adopted following the M249 as part of the move to this compatible, although different, round — firearms intended to fire the SS109 cartridge use a different rifling twist rate (1:280 mm; 1:7 inches) from the previous U.S. standard M193 5.56 mm cartridge.
The Minimi and the M249 are not exactly the same weapon — they weigh different amounts and have slightly different configurations; M249 variants can differ significantly. Although officially adopted in the early 1980s, some early production problems delayed full deployment until the turn of the decade. One thousand Minimis were purchased directly from FN for the Gulf War in 1991, as there were not enough M249s yet in service at the time. The M249 has undergone a number of variant and improvement programs, though it is scheduled to be replaced by a new lightweight machine gun — the AAI LMGA (2004 contract). In early 2005, U.S. Army ARDEC issued a solicitation for a new light machine gun; however, no selection was ever made.
The M249 is an air-cooled, gas-operated, fully-automatic-only firearm that fires from an open bolt position. It can accept belts of linked 5.56x45mm NATO (.223 inch) ammunition through the top-mounted feed tray or M16-type magazines through the side-mounted port. The latter allows a SAW gunner to use riflemen's magazines in an emergency if he runs out of belted ammunition, though this often causes jams as the magazine spring cannot adequately keep up with the weapon's high rate of fire. Linked ammunition can be fed from either a loose belt or from a plastic box containing 200 rounds, weighing 3.15 kg (6.92 lb), and is clipped under the receiver. A cloth pouch may also be used. The hard plastic box has issues with being insecurely attached and by producing noise with movement in its standard form. The M249 SAW features a built-in bipod and a tripod-mounting lug for supported fire, as well as a quick change barrel that helps prevent overheating during sustained fire. Barrels are engaged and disengaged by rotating the built-in handle, and a spare is normally carried slung in an "A-bag" by the gunner or his assistant. The forearm is designed to contain a small cleaning kit for field use, though it may not be stored there in practice.
The weapon has good firepower for its size. The latest reports on failures of M249 SAW weapons in Iraq are sometimes attributed to the age of the weapons used, and sometimes to the dusty environment in Iraq and Afghanistan. Most of the current-issue M249s in U.S. Army are more than 10 years old, which is not excessively old for a service firearm, but can reduce reliability. There have been issues with its performance at other times, particularly earlier in its development.
For training exercises, the M249 is used with the M249 Blank Firing Adaptor (BFA), essentially a steel plug which screws into the muzzle and partially blocks it. (While standard blank firing adaptors for the M16 and M4 family of weapons will fit into the barrel of the M249 SAW, their use has been abandoned in favor of a SAW-specific BFA, due to the risk of catastrophic failure of the weaker rifle BFA, which is not durable enough for sustained automatic fire.) Gas-operated weapons rely on the projectile to trap gas pressure in the system as it leaves the barrel; without this, there will be insufficient pressure to cycle the weapon. U.S. M249s are sometimes fitted with the M145 MGO, a low-power optic that fits on via a top M1913 rail, when the rail is fitted. The regular M249 does not have a rail, however. The M249 mod kit increases the weight to 16.41 pounds.
United States military doctrine describes 3,600 m as the maximum range. Effective ranges include 800 m for a point target, 1000 m for an area target, and 600 m for suppression (suppression fire is attained by keeping the maximum height of the rounds no more than 1 m off the ground). Tracer ammunition burnout is at 900 m, however. The advised rates of fire are 85 rounds per minute with no barrel changes. With a barrel change every two minutes, this increases to 200 rounds per minute. For a barrel change every minute, the rate of fire can go up to 850 rounds per minute, which is approximately equal to the cyclic rate of fire, at about 850 to 900 round/min.
In addition to its traditional use as an infantry weapon, the M249 is also sometimes used as a vehicle-mounted weapon, most often on Humvees, either in the normal roof mounting (manually or remotely operated as part of a system such as the CROWS mount, sometimes in addition to heavier weapons such as an M2 Browning machine gun), or on a swing arm mounting accessible by the front passenger seat.
M249 Para (M249E3)
The M249 Para is a commercial product (law enforcement and military sales only) by FNH USA, not a type classification. It features a metallic, retractable stock and a shorter barrel. It was designed as a paratrooper weapon, although its compact dimensions make it desirable in any combat scenario. The U.S. military did test a short-barreled variant based on a standard M249, but it would appear short-barreled M249s (not M249E4 SPWs or Mk 46 Mod 0s) have been modified to this standard in the field and are not original from factory. The difference between the FN M249 Para and the FN Minimi Para is the use of the so-called PIP (Product Improvement Program) kit developed for the M249, which is also found on all commercial M249 variants.
The following are U.S. military type classifications:
M249E4
The M249-based variant of the FN Minimi Special Purpose Weapon (SPW) has Picatinny rails mounted on the feed cover and handguard, a short barrel and a Para-style retractable stock. Some features from the SAW and Para models were removed to save weight — these include the STANAG magazine port, the tripod-mounting lug and the variable bipod.

Mk 46 Mod 0
Adopted by USSOCOM, the Mk 46 Mod 0 features an improved rail handguard and uses the standard fixed buttstock, which is significantly lighter than the E4's M5 retractable unit from FN. The Mk 46 variant differs notably from the M249 and Minimi in that it is only belt-fed, while the latter work with belts or M16-type magazines. The Mk 46 is lighter due to this change. While extremely similar, the Mk 46 Mod 0 and the M249E4 are not the same weapon.

Mk 48 Mod 0
The Mk 48 has been developed in conjunction with the U.S. Special Operations Command (USSOCOM), which has adopted the weapon and started its fielding process, starting with special operations units. The weapon's design is based on an early 7.62x51mm NATO prototype of the Minimi, modified to be a scaled-up version of the 5.56 mm Mk 46 Mod 0. Being heavily based on the Mk 46 Mod 0, the Mk 48 Mod 0 features five MIL-STD-1913 Picatinny rails (one on top of the receiver, one on each side of the forearm/handguard, one under the handguard, and one on top of the barrel), an integral folding bipod, and a tripod-mounting lug. The weapon is fitted with the same fixed, polymer buttstock as the M249, although the metallic, collapsible buttstock from the Para model can be found in some models. The carrying handle, which had been removed from the Mk 46, was reintegrated on the Mk 48 to assist the replacement of hot barrels without use of other equipment, such as heat-resistant gloves; the handle can be folded down when not in use. As with the Mk 46, the Mk 48 Mod 0 does not have an M249-type magazine feed port, in order to save weight. The weapon can be fed from a loose belt, separate belt boxes, or clip-on ammunition pouches for 100 rounds.
The high percentage of common parts (70%) with the Mk 46, M240 and M249 also provides the Mk 48 Mod 0 with easily interchangeable parts in the need of replacements. Furthermore, the Picatinny rails can be fitted with various accessories from the SOPMOD kit, such as the ECOS-N (Enhanced Combat Optical Sight) red dot sight. The Mk 48 can also be fitted with a vertical foregrip for increased controllability during sustained fire. While heavier than the 5.56 × 45 mm NATO versions of the M249 SAW due to its larger chambering and heavier barrel, the Mk 48 Mod 0 is still 17% lighter and 8.4% shorter than the M240.
The Mk 48 Mod 0 is currently in service with certain USSOCOM units, such as the U.S. Navy SEALs and Army Rangers.

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