Heckler & Koch XM8

A U.S. Marine Corps weapons instructor presents an XM8 Carbine during the Infantry Operations Chief Symposium in August 2005.

The U.S. Army's purpose in contracting for this prototype weapon was to provide replacement options for the M16 rifle after the XM29 program ran into problems. The goal was a weapon that was cheaper, lighter, and more effective than the M16 and M4 series of weapons. The XM8 was not just one weapon but a system which could be reconfigured with appropriate parts to be any one of several variants from a short-barreled personal defense weapon to a bipod-equipped support weapon. It also included an integrated optical sight and IR laser aiming module/illuminator.

The XM8 was based on the rifle module of Alliant Techsystems's XM29 OICW project, of which the weapon mechanisms were the responsibility of H&K. Following the indefinite delay of the Objective Individual Combat Weapon program, the U.S. Army requested that the contractors design stand-alone weapons from the XM29's kinetic energy and high explosive modules.

The first 30 XM8 prototypes were delivered by November 2003 for preliminary testing. Later, at least 200 developmental prototypes were procured. Among the complaints during testing was that the battery life was too low 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, which would start to melt after firing too many rounds. The main testing was largely completed, and the army pushed for funding for a large field test. However, in 2004 Congress denied $26 million funding for 7,000 rifles to do a wide scale test fielding of the XM8 in 2005. At the time the rifle still had developmental goals that were incomplete, primarily associated with the weapon's weight; the battery life had been extended, and a more heat-resistant plastic hand-guard added. The earliest product brochure lists the target weight for the carbine variant at 2.6 kg (5.7 lb) with the then current prototype at 2.8 kg (6.2 lb). The weight of the carbine prototype had since grown to 3.4 kg (7.5 lb) according to a brochure released by HK and General Dynamics in January 2005.

U.S. Army leaders test fire the compact set-up of the XM8 at Fort Benning, Georgia in August 2004.

During the same period, the army came under pressure from other arms makers to open up the XM8 to competition. The main argument was that the weapon that was being adopted was a substantially different system than for the original competition that ATK and H&K had actually won (see XM29). Other issues were that the army has a legislated obligation to prefer U.S.-based manufacturers, and that a previous agreement with Colt Defense required the army to involve Colt in certain small-arms programs. The XM8 program was put on hold in 2004. The exact reason why this happened is a matter of debate; some combination of the aforementioned technical issues, funding restrictions, and outside pressure being involved.

In 2005, the army issued a formal Request for Proposals (RFP) for the OICW Increment One family of weapons. This RFP gave manufacturers six months to develop and deliver prototype weapons with requirements very similar to the XM8 capabilities, but with the addition of a squad automatic weapon (SAW) configuration. Currently, no XM8 prototypes have been shown that actually match the capabilities of the M249 (e.g. fast barrel replacement, high sustained rate of fire, belt feed). The OICW Increment One requirement for the SAW includes fast barrel replacement and high sustained rate of fire, but leaves the ammunition feed choice up to the manufacturer.

Funding for the M320 grenade launcher, which is a single-shot under-barrel grenade launcher similar to the M203 that was originally intended for the XM8, was approved. The launcher is actually heavier than the M203, but does offer some advantages. The XM320 was designed for use with the existing inventory of M16s and M4s and is also compatible with the XM8. It can also be used as a stand-alone weapon.

As of July 19, 2005, the OICW Increment One RFP was put on an eight-week hold, with an indication given that the program was being restructured as a joint procurement program. On October 31, 2005, the OICW Increment One RFP was cancelled.

In an article in Jane's Defence Weekly, April 26, 2006 (Vol 43, page 30) it is stated that "The US Army has again delayed the procurement of its future infantry weapons, this time for more than five years, and is working to field two interim guns in the meantime".

General Dynamics was involved in latter stages and H&K had plans to produce the rifle at a plant in Georgia. H&K was British-owned at the start of the project, but was later bought back by a group of German investors. Engineering work was done at facilities in the United States and Germany.

Near cancellation

A prototype XM8 carbine - lacking PCAP device on the side rails. Also has the open 'duckbill' rather than 'birdcage' style flash suppressor

The U.S. military's XM8 program was almost canceled in the autumn of 2005 after being suspended earlier that year, but was limited to the use of Marines. Had this program not been specified, the XM8 system may have faced competition from weapons such as from the FN SCAR, Bushmaster ACR and HK416. It was later altered and entered as a candidate for the SCAR competition but was unsuccessful.[1]

XM8 testing; One shooter is kneeling with an XM8 Carbine and a XM320 (a 40 mm grenade launcher) attached, while the other uses the XM8 sharpshooter (designated marksman) variant.

An XM8 compact carbine variant with buttcap attached, fired by a U.S. Army weapons tester.

The XM8 is a selective-fire 5.56mm assault rifle, firing from a closed rotary bolt. Its design and functioning is similar to that of the Heckler & Koch G36 assault rifle, of which it is a derivative.

Navy PASKAL operators on standby during 57th National Day Parade Of Malaysia.

H&K XM8 Carbine attached with H&K AG36 Underbarrel Grenade Launcher of Royal Malaysian Navy's special forces, PASKAL.

For much of its life, four different models were proposed: a compact PDW (personal defense weapon) with a 241 mm (9.5 in) barrel, a carbine with a 317 mm (12.5 in) barrel, a sniper and automatic rifle variant, both with 508 mm (20 in) barrels. In addition a Light machine gun with a 100-round dual drum Beta C-Mag is proposed. Accessories such as optical sights, a grenade launcher, and a bipod were integrated using a new system which allows for precision attachment (so that, for example, scopes do not have to be readjusted each time they are attached). Like the M4 and M16, the XM8 was chambered for the standard 5.56×45mm NATO round and was normally equipped with a 30-round plastic box magazine also used in the G36. Although, this meant that the magazine housing was not compatible with M4 and M16's metal STANAG magazine without using an adaptor. A 100-round dual drum Beta C-Mag style magazine could also be used.

One of the XM8's unique features was its modularity. In addition to attachments mentioned above, this modularity allowed for quick repairs, barrel length changes, and even caliber changes in the field. Along with its basic components, the XM8 would have complemented the XM29, with such features as identical accessory mounts.

The number and type of variants in the family varied over its lifetime, this overview with three main versions is based from a press release in the early 2000s.

• XM8 compact carbine: 229 mm (9 in) barrel, PDW configuration, collapsing stock[4] or buttcap; muzzle velocity 720 m/s (2,362 ft/s)
• XM8 carbine with XM320 grenade launcher: 317 mm (12.5 in) barrel; muzzle velocity 815 m/s (2,674 ft/s)
• Automatic rifle: 508 mm (20 in) barrel, muzzle velocity 916 m/s (3,005 ft/s)
• Designated marksman rifle: 508 mm (20 in) barrel, integrated folding bipod, 4X sight, 30/100-round magazine; muzzle velocity 916 m/s (3,005 ft/s)s[5]
• Light machine gun: heavy 508 mm (20 in) barrel with integrated folding bipod, rate of fire 600-750 rpm

While the XM8 fell out of favor with the U.S. Armed Forces, Heckler & Koch sought to market the rifle globally. In the meantime, the Malaysian Armed Forces expressed interest in using the rifle and by 2007 openly stated its intention to purchase the XM8 rifle. By 2010, the Royal Malaysian Navy special unit PASKAL began using the XM8 along with other Heckler & Koch assault rifles including the HK416 and G36.[6][7][8]

• AN-94
• XM29 OICW
• XM25 Individual Airburst Weapon System
• Heckler & Koch G36
• Kinetic projectiles
• Kinetic energy penetrator
• M320 grenade launcher
• Adaptive Combat Rifle, modular rifle system.
• Beretta ARX160
• FN SCAR
• Barrett REC7

Wikimedia Commons has media related to: XM8 (category)

• Picatinny article from 2004 about XM8 (.mil)
• Defense-Update.com article on XM8
• Global Security.org article about XM8
• HKsystems.com overview