Heckler & Koch HK416
The HK416 is an assault rifle designed and manufactured by Heckler & Koch. It is an improved version of the M4 carbine with many changes, most notably a new style gas system borrowed from the HK G36. It is available as a complete firearm or as an upper receiver kit that fits on any AR-15 type lower receiver.
The US Army’s Delta Force collaborated with the German arms maker to develop the new carbine. Delta replaced its M4s with the HK416 in 2004 after tests revealed that the piston operating system significantly reduces malfunctions while increasing the life of parts.
The project was originally called the HK M4, but this was changed in response to a trademark infringement suit filed by Colt Defense. The weapon has been tested by the United States military and is in use with some law enforcement agencies and special operations units. It has been adopted as the standard rifle in two NATO nations as well.
Design details
The HK416 uses a proprietary gas system derived from the HK G36, replacing the direct impingement gas system used by the standard M16/M4. The HK system uses a short-stroke piston driving an operating rod to force the bolt carrier to the rear. This design prevents combustion gases from entering the weapon’s interior, a shortcoming with direct impingement systems. The reduction in heat and fouling of the bolt carrier group increases the reliability of the weapon and extends the interval between stoppages. It also reduces operator cleaning time and stress on critical components.
The HK416 is equipped with a proprietary accessory rail forearm with MIL-STD-1913 rails on all four sides. This allows most current accessories, used on M4/M16-type weapons, to be fitted to the HK416. The HK416 rail forearm can be installed and removed without tools by using a bolt locking lug as the screwdriver. The rail forearm is of the 'free-float' variety; it does not contact the barrel and improves accuracy.
The HK416's barrel is cold hammer-forged with a 20,000 round service life. The cold hammer-forging process provides a stronger barrel for greater safety in case of an obstructed bore or for extended firing sessions. This includes "OTB" (Over-the-beach) capability; the HK416 can be safely fired after being submerged in water and not completely drained.
Variants
The HK416 is currently available in four different barrel lengths: the D10RS model with a 264 mm (10.4 in) barrel, the 368 mm (14.5 in) barrel length D14.5RS, the D16.5RS fitted with a 419 mm (16.5 in) and the 505 mm (19.9 in) length barrel of the D20RS. The HK417 is a larger version of the HK416 chambered for the full-size 7.62x51mm NATO rifle cartridge. Civilian variants of the HK416 and HK417 were announced in 2007, named MR223 and MR308. Both are semi-automatic rifles with several 'sporterized' features. At the 2009 SHOT Show, these two firearms were introduced to the American civilian market renamed respectively MR556 and MR762.
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