The Heckler & Koch HK416 is a collaboration project between the US Army Delta Force R&D department and the German firearms company Heckler & Koch, at the request of US Army combat veteran Larry Vickers. The goal was to make a M4 variant that has a shorter profile and lacks the AR-15's direct impingement system. The rifle was originally named the HKM4, but was later changed to HK416 after a law suit was filed by Colt Defense over the trademark for the M4 name. The project took inspiration from the HK50, XM8, and L85A2 endeavours of H&K.

Chambered in 5.56x45mm NATO, the HK416 is a short-stroke gas piston operated, rotating bolt, selective fire automatic carbine. Feeding from NATO STANAG magazines, the rifle has a rate of fire of 700-900 rounds per minute. The rifle's foldable iron sights provide accurate fire out to 300 meters. It features a proprietary short-stroke piston mechanism developed by H&K for the G36 as opposed to the direct gas impingement system used by most AR-15 derivatives. This piston system enhances the rifle's reliability once it is dipped in water or sand. It has an adjustable telescopic buttstock.

The rifle features Picatinny rail placements along the top of the upper receiver, as well as on the top, bottom, and sides of the RIS handguard. The rails are compatible with various accessories such as optical sights, lasers, and flashlights. The handguard does not come in contact with the barrel, which is "free-floating" to improve the rifle's accuracy by reducing the impact of the handguard's movements on the barrel. The bottom rails can mount a fore-grip or a 40mm grenade launcher (typically the AG36 or M320 launchers).

Military/Police units all over the world are adopting HK416 variants due to their reliability, performance, and modularity. Starting with the Norwegian army (HK416N), the United States special operation groups such as Delta Force and DEVGRU SEALs have followed suit and begun the process of phasing out their M4A1 carbines for HK416s. The French army is also planning on replacing their FAMAS F1 with the HK416F.


The HK416 has yet to replace the G36 as the main service rifle of Germany's Bundeswehr. However, they have purchased some HK416A5 rifles which were given the designation of G38 to replace the MP5 as standard emergency firearm for their police units,while the HK416A7 was adopted by the German Special Commando Forces and the German Naval Special Commando Forces under the name G95 in 2017.

The US Marine Corps' M27 Infantry Automatic Rifle is a beefed up version of the HK416, designed to partially replace the M249 Squad Automatic Weapon light machine gun in a suppressive fire role. The M27 IAR emphasizes a more marksman approach over the belt-fed M249 SAW, and is more maneuverable in CQB scenarios. It is fitted with a bipod for stability.