M27 Infantry Automatic Rifle

The M27 Infantry Automatic Rifle (M27 IAR) is a 5.56×45mm NATO selective-fire rifle developed from the Heckler & Koch HK416.

The M27 Infantry Automatic Rifle (M27 IAR) is a 5.56×45mm NATO selective-fire rifle developed from the Heckler & Koch HK416. It is used by the United States Marine Corps and was selected to replace the M249 in the infantry automatic rifle role, later being issued more widely to Marine infantry units.

Development

The M27 IAR emerged from the U.S. Marine Corps Infantry Automatic Rifle program, which aimed to field a lighter, more maneuverable automatic weapon than the belt-fed M249 for certain infantry roles.

Design

The weapon is derived from the HK416 and uses a gas-operated, short-stroke piston system with a rotating bolt. It is chambered for 5.56×45mm NATO and is commonly described as firing from a closed bolt.

Service use

The U.S. Marine Corps adopted the M27 IAR after testing and evaluation, and it entered service in the infantry automatic rifle role. Later reporting indicates it was also issued more broadly within Marine infantry units as a standard rifle.

Specifications

Commonly reported specifications include a 420 mm barrel, an overall length of roughly 838–937 mm depending on stock position, and an empty weight of about 3.6 kg. Standard magazines are 30-round STANAG types.