The HK416 is an assault rifle designed and manufactured by Heckler & Koch to be an improved version of the M4 Carbine pattern firearm. 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. It replaced its M4s with the H&K 416 in 2004 after tests revealed that the piston operating system significantly reduces malfunctions while increasing the life of parts.
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 retract. This design prevents propellant gases from entering the weapon’s interior, a traditional short-coming with direct gas 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 all current accessories, sights, lights, and aimers used on M4/M16-type weapons to be fitted to the HK416. The HK416 rail forearm can be installed and removed without tools, using a bolt locking lug as the screwdriver. The rail forearm is of the ‘free-float’ variety; it does not contact the barrel. This allows for improved accuracy potential.
The HK416’s barrel is cold hammer-forged. This allows the barrel to maintain its accuracy for over 20,000 rounds, with minimal degradation of muzzle velocity. The cold hammer-forging process also allows for improved operator safety during obstructed bore occurrences or after 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.