Heckler & Koch HK416

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 project was originally called the HKM4, but this was changed in response to a trademark infringement suit filed by Colt Defense. It is speculated that '416' is a reference to the M4 and M16 it's designed to compete with. So far the weapon has reportedly been tested by the United States military as well as some law enforcement agencies. It is only available to government and military organizations currently, but there are plans for a semi-automatic civilian version, the MR223, to be released in 2008.

Design
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.

The HK416 is currently available in four different barrel lengths:
 * D10RS (10.4 inch / 264 mm)
 * D145RS (14.5 inch / 368 mm)
 * D165RS (16.5 inch / 419 mm)
 * D20RS (20 inch / 508 mm)

Related Weapons
The HK417 is a larger version of the HK416 chambered for the 7.62x51mm NATO round. The HK417 is designed for military and law enforcement use. The HK417 and HK416 have a relationship similar to the AR-10 and AR-15.

Evaluation
In July 2007, the US Army announced a limited competition between the M4 carbine, FN SCAR, HK416, and the previously-shelved HK XM8. Ten examples of each of the four competitors were involved. Each weapon was fired for 6,000 rounds in an "extreme dust environment." The purpose of the shootoff was for assessing future needs, not to select a replacement for the M4. The XM8 scored the best, with only 127 stoppages in 6,000 total rounds, the MK16 SCAR Light had 226 stoppages, while the HK416 had 233 stoppages. The M4 carbine scored "significantly worse" than the rest of the field with 882 stoppages. The results have been thrown into question due to the M4 scoring 307 jams in a previous dust chamber test conducted only a few months before with the same conditions and lubrication.

Variants
The MR223 is a semi-automatic civilian version of the HK416 announced in 2007 and slated to be released in the third quarter of 2008.

Users

 * 🇲🇾 malaysia - Royal Malaysian Police Counter Terrorist special forces, Pasukan Gerakan Khas (PGK).
 * 🇮🇩 indonesia - Indonesian Marine Corps Counter Terrorist Unit, Detasemen Jala Mengkara (Denjaka).
 * 🇳🇱 netherlands - The Netherlands Army special forces unit Korps Commandotroepen selected the HK416 over other tested assault rifles to replace their Diemaco C8 assault rifles. The weapon is shown on several photos from the unit's recruitment day. The HK416 is currently (2008) the standard assault rifle of the unit.
 * 🇳🇴 norway - On April 11, 2007, the Norwegian Ministry of Defence signed a contract for an initial shipment of 8,200 rifles to serve as its new standard assault rifle, replacing the AG-3 that has been in use since 1967. It is slightly modified, with a different stock and pistol grip. The deal also included the purchase of 6500 HK MP7. Delivery is expected in the first half of 2008.
 * 🇹🇷 turkey - Turkish Army has tested HK416 and reportedly decided to adopt it as a replacement for the currently issued G3 rifle. It is yet unknown whether the weapons will be produced by HK in Germany or locally by a national manufacturer. It is currently designated Mehmetcik 1.
 * 🇺🇸 united states - It is used by the U.S. Army's counterterrorist Delta Force (1st Special Forces Operational Detachment-Delta), various other Special Operations Command units including DEVGRU, US Capitol Police SWAT, and formerly, the US Army's Asymmetric Warfare Group. The latter has since had to turn in their HK416's.