The M240B Machine Gun



By Scott R. Gourley

While the equipment spotlight for the U.S. Army''s initial brigade combat team remains focused on the Army''s new interim armored vehicle (IAV), many 3rd Brigade infantrymen now training on the firing ranges at Fort Lewis, Wash., seem equally excited about another anticipated piece of hardware being fielded: the M240B 7.62 mm machine gun. Firing the same 7.62 mm belt ammunition as the M60-series machine gun, the M240B was introduced during the late 1990s to replace the M60 in infantry, armor, special operations forces and selected combat engineer units.

"The M240B provides a much more reliable weapon system than the M60," says Rob Zienowicz, who handles the M240B as chief of the crew-served weapons team within the Army''s Office of the Product Manager for Small Arms.

According to Zienowicz, Army plans had originally called for replacement of the M60 by the M249 5.56 mm squad automatic weapon (SAW), which was viewed by many as "the Army''s machine gun." "There was some concern about the loss of firepower with the 5.56 mm round. Even though the SAW is lighter, there was concern about losing the firepower in exchange for mobility enhancement, so the Infantry was pushed to retain the same 7.62 mm firepower through a replacement for the M60," he says.

The dilemma led to categorizing the M249 as a light machine gun and the M60 as a medium machine gun. Seeking the optimum mix of firepower and reliability in the 7.62 mm arena, the Army embarked on a program initially characterized as an upgrade to the medium machine gun.

"The original program identified a kit to upgrade existing medium machine guns in the Army inventory," Zienowicz continues. "The plan was to select the best weapon from an upgraded M60 or an upgraded M240. The Army already had a coaxial version of the M240, so it opened the door to upgrade either the M60 or M240. There was basically a shoot-off between the two weapons: One was the M60E4, and the other was the M240E4, which became known as the M240 Bravo."

The coaxial M240 used in Army main battle tanks was a version of the Belgian MAG 58, produced by FN Herstal. The M240 is now being produced by its U.S. subsidiary, FN Manufacturing Inc. (FNMI).

During the shoot-off competition, the M240E4 reportedly demonstrated greater reliability; it had an operational stoppage rate of less than one stoppage per 10,000 rounds for the M240E4 versus one stoppage in fewer than 1,000 rounds for the M60E4. This reliability came at a weight penalty, however, when compared with the M60E4. Moreover, Zienowicz notes that recent operational testing has pegged M240B reliability at one stoppage in more than 40,000 rounds.

Along with increased reliability, M240B performance characteristics include gas operation, fixed headspace and timing, muzzle velocity of 2,800 feet per second, maximum range of 3,725 meters (tracer burnout at 900 meters) and operator adjustable rates of fire of 750 or 950 rounds per minute.

Based on the initial shoot-off competition, Army representatives took 1,200 M240 coaxial machine guns already in the inventory and applied the upgrade kit. "Some of the first 1,200 guns were originally made back in the 1970s," Zienowicz says. "So we sent them over to FNMI, which won the competition, and it did some minor upgrades to bring the baseline configuration guns up to the latest configuration with various engineering changes incorporated. Then FNMI applied the upgrade kit that included a buttstock, a new top cover with an integrated military standard rail for mounting accessories, a heat shield, a hand guard, new barrels (the barrel is different from the coaxial version in that it has a front sight, flash suppressor and carrying handle), a rear sight, a bipod and a dust cover for the ejection port."

Following that 1996-97 upgrade effort, the Army received additional funding for new-manufacture M240B weapons. The acquisition featured a multiyear contract award with funding provided in fiscal year (FY) 1997, FY 1999 and FY 2000. (FY 1998 was initially a "zero year" in the Army budget, but Congress added a $14.4 million "plus-up.") Along the way, government and industry designers have introduced a new buffer system to the gun. Goals of the new buffer system included saving money, reducing weight and improving overall weapon system performance.

Zienowicz describes the enhancement as "a hydraulic buffer system similar to the one that''s used on the M60 and the M249. It absorbs the recoil energy from inside the receiver. When we initially fielded the M240, we fielded it with a flex-mount, a mount with shock absorbers. The flex-mount weighs almost 5 pounds and costs about $475, so we''ve replaced it with this new buffer system inside the gun and a couple of other parts . Overall we''re saving about 3 pounds and a couple of hundred dollars on the total system. The receiver also moves a lot less for reduced felt recoil on the gunner''s shoulder. We''ve received a lot of praise for that. Also, although we haven''t been able to quantify it yet, there''s an improvement in target acquisition. If a machine gunner is using optics on the weapon system, he''s able to track the target hits through the optic, but before he could not."

The M240B program is still in production with full execution of options contained under the multiyear production contract. Full-option execution was possible as a result of just over $12 million that the Army identified for the program in FY 2000 with an additional FY 2000 Congress plus-up of $28 million to help fill out Army procurement objective levels. Further funding was also received in FY 2001.

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