XM8 Future Combat Rifle / Lightweight Assault Rifle
Modular Assault Weapon System
The XM8 Future Combat Rifle is intended to replace existing M4 Carbines and select 5.56mm x45 weapons in the US Army arsenal.
The XM8 is a derivative of the Heckler-Koch G36 assault rifle, and is similar to that rifle in design and functioning. 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 prototype weighs 6.4 pounds, with an objective weight of 5.7 pounds. PEO claims it takes one third the time to train a Soldier on the XM8 than the current weapon system.
The XM8 is also more reliable. Unlike the current M4 and M16, the XM8 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, and it reduces cleaning time by as much as 70 percent. PEO says the XM8 can fire 20,000 rounds without stoppages or malfunction. The first XM8 tested fired 15,000 rounds without cleaning or lubrication without a first misfire.
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 XM8 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. 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. 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 apiece, 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.
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. 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.
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 investigated the potential of the XM8 as the lightweight assault rifle for the Army's Objective Force.
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 was 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.
An early 2003 strategy change at the Program Executive Office, Soldier sped up the development of a potential replacement of the Army's assault weapons. They moved from an "evolutionary approach" to "spiral development." Under the evolution strategy, developers planned to build a complete system, then improve on it. The first built would be about an 80 percent solution. The second about 90 percent and the third would be 100 percent. That approach would take too long to get new technology in the soldiers' hands. Under the spiral approach, the team broke the system into subsystems. This allows the parts to mature individually before being integrated into a single system.
With the first 30 prototypes delivered as of November 2003, XM8 prototypes entered testing. 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. Problems identified in testing were low battery life for the weapon's powered sight system, and some ergonomics issues. Two other key issues were reducing the weapon's weight and increasing the heat resistance of the hand guard.
The Army ordered 200 XM8's for the Army Test and Evaluation Command to test during the last quarter of 2004. Improvements will be made based on soldier and test feedback before the final three-months of operational tests, which began in fall 2004. The final decision will be up to the Army's senior leadership, but in early 2004 weapons officials said they were confident the XM8 weapon system will be adopted. If all went well, the XM8 would be ready for fielding by late summer 2005.
In 2004 Congress denied $26 million dollars funding for 7,000 rifles for a test fielding of the XM8 in 2005. The battery life had been extended, and a more heat-resistant plastic hand-guard added. But the rifle still had goals that were unmet, primarily associated with the weapon's weight. The earliest product brochure lists the target weight for the carbine variant at 5.7 lb (2.6 kg) with the then current prototype at 6.2 lb (2.8 kg). The weight of the carbine prototype has since grown to 7.5 lb (3.4 kg) according to a brochure released by HK and General Dynamics in January 2005.
During 2004 the Army came under pressure from other arms makers to open up the XM8 to competition. Their main arguments was that the weapon being adopted was substantially different from the original XM29 competition that ATK and H&K had actually won. In addition, the the Army has a legislative obligation to give preference to US-based manufacturers, and also had an agreement with Colt Defense that required the Army to involve Colt in certain small-arms programs.
Following complains about the non-competitive procurement of the XM8 system from Heckler-Koch USA, in November 2004 the Army re-opened the bidding for the 5.56mm Modular Weapon System Family
contract to other companies. In July 2005 the Army suspended the OICW Increment 1 program to review the requirements for the effort to replace the current M16 rifle and M4 carbine. The requirements will be rescoped as a Joint Services effort.
On July 19, 2005 the Army announced it had temporarily suspended the Request for Proposal (RFP) for the acquisition of a new family of small weapons - Objective Individual Combat Weapon Increment 1 (OICW-1) - in order to incorporate joint requirements. The Army’s proposal has received interest from the other military services, and is further supported by several internal reviews reinforcing the increase in the potential for joint use.
Congressional notification has been made and the suspension of the program allowed joint requirements to be viewed and incorporated through the Joint Capability and Integration and Development System process, which began immediately. Original solicitation started May 11, 2005, and is temporarily suspended effective July 19, 2005, until the Joint Requirements Oversight Committee (JROC) convenes, which was scheduled for early September. Upon the JROC’s completion, the committee will issue a memorandum, which incorporates any new joint OICW-1 requirements. The RFP will be amended accordingly, and issued with a revised effective date for receipt of proposals.
On 31 October 2005, the XM8 program was formally suspended, "pending further US Army reevaluations of its priorities for small caliber weapons, and to incorporate emerging requirements identified during Operation Enduring Freedom and Operation Iraqi Freedom. The Government will also incorporate studies looking into current capability gaps during said reevaluation."
XM8 Carbine Specifications