The XM8 Future Combat Rifle is intended to replace existing M4 Carbines and select 5.56mm x45 weapons in the US Army arsenal beginning as early as the fourth quarter of FY05.
In October 2002 ATK (Alliant Techsystems) was awarded a $5 million contract modification from the U.S. Army Armament Research, Development, and Engineering Center (ARDEC), Picatinny, N.J., to develop the new XM8 Lightweight Assault Rifle. ATK Integrated Defense, Plymouth, Minn., and teammate Heckler and Koch, Oberndorf, Germany, will support the rapid development program, which will investigate the potential of the XM8 as the lightweight assault rifle for the Army's Objective Force.
The XM8 will be based on the kinetic energy weapon that is part of the XM29 next-generation infantry weapon system (formerly the Objective Individual Combat Weapon) currently under development by ATK Integrated Defense. The kinetic energy weapon, which fires 5.56mm ammunition, will provide maximum commonality in components and logistics with the XM29 system.
The XM8 will provide lethality performance comparable to the currently fielded M4 carbine rifle, while weighing 20 percent less than the M4 because of advanced technologies developed for the XM29 program.
The XM8 Lightweight Assault Rifle will reduce the 21st century soldier's load and increase his mobility - two very important aims of the Army's Objective Force Warrior and Land Warrior initiatives. The progress made to reduce weight and improve performance on the XM29 program is key to the decision on accelerating the development of the XM8, which is integrated with the Army's efforts to transform to a more lethal and rapidly deployed fighting force as part of its Objective Force.
ATK Integrated Defense is the system integrator on the XM29 program. Teammates on the program are Heckler and Koch, weapon development; ATK Ammunition Systems, Arden Hills, Minn., ammunition development; Brashear LP, Pittsburgh, Pa., integrated full solution fire control; and Omega, Columbus, Ga., training systems.
The XM8 is a true family of weapons with different barrel lengths designed to address all the needs of an infantry squad. The standard model is expected to be lighter than the M4 carbine and no larger in size. There's also a sharpshooter version for increased range; a compact version for cramped quarters; and an auto-rifle version for a squad-automatic weapon. The XM8 family has a 9-inch compact, 12.5-inch carbine and a 20-inch sharpshooter and automatic rifle. The 12.5-inch carbine is 6.4 pounds with an objective of 5.7 pounds and is 33 inches with its adjustable stock extended. The M-16 A2 is 39.63 inches long and 8.79 pounds with a 30-round magazine.
Internally, the XM8 uses a rotary locking bolt system that functions and fieldstrips like those used in the M-16 rifle and M-4 carbine, according to the XM8 manufacturer's - Heckler Koch - Website. The bolt is powered by a unique gas operating system with a user-removable gas piston and pusher rod to operate the mechanism. Unlike the current M-4 and M-16 direct gas system with gas tube, the XM8 gas system does not introduce propellant gases and carbon back into the weapon's receiver during firing.
While the XM8 was not exposed to battlefield conditions, it's still a feat the current service rifle hasn't come close to rivaling, said Rich Audette, deputy project manager for PM Soldier Weapons. During their Oct. 20-23 2003 trip to Germany, the weapons experts said they were impressed after watching Heckler Koch engineers fire four high-capacity magazines, with 100 rounds a piece, in less than five minutes.
This improved reliability can be credited to differences in the XM8's operating system from the one in the M16. For instance, a thin gas tube runs almost the entire length of the barrel in all of the M16 variants. When the weapon is fired, the gases travel back down the tube into the chamber and push the bolt back to eject the shell casing and chamber a new round. The XM8's gas system instead is connected to a mechanical operating rod, which pushes back the bolt to eject the casing and chamber the new round each time the weapon is fired. So there's no carbon residue constantly being blown back into the chamber, reducing the need to clean the weapon as often. You don't get gases blowing back into the chamber that have contaminates in them. The XM8 also has a much tighter seal between the bolt and the ejection port, which should cut down on the amount of debris that can blow into the weapon when the ejection port's dust cover is open.
The XM8 is part of the Army's effort to perfect an over-and-under style weapon, known as the XM29, developed by Alliant Techsystems and H&K. It fires special air-bursting projectiles and standard 5.56mm ammunition. But the XM29 still is too heavy and unwieldy for Army requirements. Instead of scrapping the XM29, the Army decided to perfect each of XM29's components separately, so soldiers can take advantage of new technology sooner. The parts would be brought back together when lighter materials become available. The XM8 is one of those components.
From December 2003 through late May 2004, soldiers got a chance to fire the prototypes in desert, tropical and arctic environments. A limited-user test then was conducted, possibly at Fort Campbell, Ky., where soldiers test the prototypes for about three weeks while training in offensive and defensive scenarios. Improvements will be made based on soldier and test feedback before the final three-months of operational tests, which are scheduled to begin in fall 2004. The final decision will be up to the Army's senior leadership, but weapons officials said they were confident the XM8 weapon system will be adopted. If all goes well, the XM8 could be ready for fielding by late summer 2005.
Beginning life as the 5.56mm KE (kinetic energy) component of the 20mm air-bursting XM29 Objective Individual Combat Weapon (OICW), the XM8 Lightweight Modular Carbine System represents the state-of-the-art in 5.56x45mm NATO assault rifles. Developed by the US Army's office of Project Manager for Soldier Weapons located at Picatinny Arsenal, New Jersey in close conjunction with the US Army Infantry Center, the XM8 Future Combat Rifle is intended to replace existing M4 Carbines and select 5.56mm x45 weapons in the US Army arsenal beginning as early as the fourth quarter of FY05. Once adopted, the M8 Carbine will replace the aging M16/M4 family of weapons, which have been in service for nearly four decades, longer than any previous US service rifle. The M8 Carbine will be up to 20% lighter than a comparably equipped M4 Carbine MWS and yet offer additional features and performance unavailable currently in any assault rifle in the world.
As a direct development of the separable OICW (XM29) KE or Kinetic Energy module, the M8 Carbine will share a high degree of common parts and training and maintenance procedures to lessen the required support for the "family" of XM8 weapons. Being developed are four XM8 variants, which include a baseline carbine, a sharpshooter variant, an automatic rifle variant, and the ultra-compact carbine variant. A unique feature of the XM8 modular weapon system is the ability to easily and quickly reconfigure the weapon from one variant to the other to meet changing mission requirements, to include caliber conversion.
This modularity includes the exchange of interchangeable assembly groups such as the barrel, handguard, lower receiver, buttstock modules and sighting system with removable carrying handle. In addition and in parallel, the new XM320 quick detachable single-shot 40mm grenade launcher with side-opening breech and LSS lightweight 12 gauge shotgun module can be easily added to the XM8 by the user in the field without tools. The unique buttstock system allows the operator exchange buttstocks without tools from the standard collapsible multi-position version, to an optional buttcap for maximum portability or an optional folding or sniper buttstock with adjustable cheekpiece for special applications. Internally the XM8 employs a combat-proven robust rotary locking bolt system that functions and fieldstrips like that used in the current M16 rifle and M4 carbine. However this bolt is powered by a unique gas operating system that employs a user removable gas piston and pusher rod to operate the mechanism. Unlike the current M4/M16 direct gas system with gas tube, the XM8 gas system does not introduce propellant gases and the associated carbon fouling back into the weapon's receiver during firing. This greatly increases the reliability of the XM8 while at same time reducing operator cleaning time by as much as 70%. This system also allows the weapon to fire more than 15,000 rounds without lubrication or cleaning in even the worst operational environments. A cold hammer forged barrel will guarantee a minimum of 20,000 rounds service life and ultimate operator safety in the event of an obstructed bore occurrence.
The XM8 has fully ambidextrous operating controls to include a centrally located charging handle that doubles as an ambidextrous forward assist when required, ambidextrous magazine release, bolt catch, safety/selector lever with semi and full automatic modes of fire and release lever for the multiple position collapsible buttstock. The operating controls allow the operator to keep the firing hand on the pistol grip and the weapon in the firing position at all times while the non-firing hand actuates the charging handle and magazine during loading and clearing. Major components of the weapon are produced from high-strength fiber reinforced polymer materials that can be molded in almost any color to include OD green, desert tan, arctic white, urban blue, brown and basic black. Surfaces on the XM8 that interface with the operator are fitted with non-slip materials to increase comfort and operator retention. The XM8 uses 10 or 30-round semi-transparent box magazines and high-reliability 100-round drum magazines for sustained fire applications.
Special integral flush mounted attachment points are located on the handguard and receiver to allow the quick attachment of targeting devices. Unlike MIL-STD-1913 rails, the XM8 attachment points do not add additional weight, bulk and cost to the host weapon, and will accept MIL-STD-1913 adapters to allow for the use of current in-service accessories. The attachment points for the standard multi-function integrated red-dot sight allow multiple mounting positions and insure 100% zero retention even after the sight is removed and remounted. The battery powered XM8 sight includes the latest technology in a red dot close combat optic, IR laser aimer and laser illuminator with back-up etched reticle with capability exceeding that of the current M68-CCO, AN/PEQ-2 and AN/PAQ-4. This sight will be factory zeroed on the weapon when it is delivered and does not require constant rezeroing in the field like current rail-mounted targeting devices. The XM8 will be fully compatible with future Land Warrior technology and components.
The US XM8 Carbine is being designed at the HK Defense design center in Sterling, Virginia and will be produced and assembled in the United States at the new Heckler Koch manufacturing plant located in Columbus, Georgia, adjacent to Fort Benning. The unit cost of the XM8 will be less than that of the current M4 Carbine and will guarantee the American war fighter uncompromising performance far exceeding that of current in-service M4 Carbines.
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