The M27 Infantry Automatic Rifle (IAR) is a 5.56mm, select-fire assault rifle, based on the HK416 by Heckler & Koch. It is used by the United States Marine Corps (USMC) and is intended to be issued to all infantry riflemen as well as automatic riflemen.
The M27 is based on the H&K HK416. It features a gas-operated short-stroke piston action with a rotating bolt and a free-floating barrel. The handguard has four MIL-STD-1913 Picatinny rails for use with accessories and optics. Alternate calibers other than 5.56 mm are being considered for the M27.