The Marine Corps’ experimental battalion, the 3rd Battalion, 5th Marines, has issued the M-27 Infantry Automatic Rifle to all their riflemen to evaluate it as a possible new service rifle for the Corps.
The M-27 Infantry Automatic Rifle (IAR), based on the Heckler & Koch HK416, was purchased by the Marines to enhance an automatic rifleman’s maneuverability over the M-249 Squad Automatic Weapon (SAW). It will fill the Squad automatic rifle role in selected units.
The standard optic is the Trijicon ACOG Squad Day Optic (SDO), the Sight Unit, SU-258/PVQ Squad Day Optic. It is a 3.5×35 machine gun optic that has a Ruggedized Miniature Reflex (RMR) sight screwed on top for close-quarters engagements under 100 meters. Created for the SAW, the day optic offers slightly less magnification, but longer eye relief than the ACOG Rifle Combat Optic (RCO) on M-16s and M-4s. The longer relief helps reduce injury risk from recoil.
Each M27 gunner is equipped with twenty-two 30-round magazines approximating the individual combat load of an M-249 SAW gunner, although the M-27 gunner would not expected to carry all 22 magazines.
The U.S. Marine Corps has contracted to purchase 6,500 M-27s to replace a portion of the M249 light machine guns currently employed by automatic riflemen within Infantry and Light Armored Reconnaissance Battalions. Approximately 8,000–10,000 M249s will remain in service at the company level to be used at the discretion of company commanders.
The test battalion is set to deploy overseas as part of the 31st Marine Expeditionary Unit. Every rifleman in 3/5 was issued an M-27 IAR during the 28-day Integrated Training Exercise at Marine Corps Air-Ground Combat Center 29 Palms, California. The ITX, is the primary pre-deployment workup for deploying battalions and evaluators collect a great amount of performance data to compare rifles.
The M-4 Carbine and the M-27 IAR have the same fire controls and ergonomics but M-27 has a longer effective range at 550 meters compared to the M4’s 500. The M-27s free-floating barrel, surrounded by MIL-STD-1913 Picatinny rails for use with accessories and optics, is inherently more accurate as it allows the barrel to vibrate consistently from shot to shot. The M-27 features a gas-operated short-stroke piston action with a rotating bolt. This gas-piston rifle system reduces the amount of time it takes to resolve malfunctions on the IAR compared with the M-249. The proprietary gas piston system is thought by some to be more reliable and reduce wear and tear.
The Marines are moving into this test deliberately and should produce valid results.
Featured image courtesy of