Heckler & Koch HK XM8

Heckler & Koch HK XM8 History

The Heckler & Koch HK XM8 is an experimental modular assault rifle system that the US Army is testing as their next standard assault weapon system. The weapon is designed to replace the long-lived Colt M16 rifle and M4 carbine forms.

As such, the XM8 should evolve into its own family of automatic weapons, including a basic assault rifle (which can also be used as a designated marksman rifle), a shortened carbine (supporting the experimental XM320 grenade launcher), a dedicated sniper version, and a Choose a compact carbine with a foldable stock. Despite promising results from the program, the XM8 was discontinued in April 2005 and officially retired in October of the same year.

The XM8 series will include a 9-inch compact, a 12.5-inch carbine, and a 20-inch sniper and automatic rifle die. The 12.5-inch carbine weighs 6.4 pounds and has a target of 5.7 pounds, with a barrel length of 33 inches and an adjustable stock fully extended. By comparison, the M16A2 is 39.63 inches long, weighs 8.79 pounds, and comes with a full 30-round magazine. Internally, the XM8 used a twist-lock pneumatic bolt-action, which functions like the M16 rifle and M4 carbine, and was stripped to replace it.

The bolt is powered by a unique gas operating system with a user-removable gas piston and a push rod (HK G36 derived system) for operating the mechanism. Unlike the current M4 and M16 air duct direct air supply systems, the XM8 air supply system does not return propellant and carbon back to the gun's receiver during firing, which reduces fouling. The XM8 is loaded with standard NATO 5.56x45mm cartridges, fed by a curved, detachable 30-round magazine.

The Beta C-Mag 100-round drum magazine also received further support.

Design work on the XM8 dates back to 2002, with prototypes completed in 2003 and 2004. XM8 was resurrected to judge the SCAR races XM8 lost.

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