Caliber: 5.56x45mm NATO
Action: Gas operated, rotating bolt
Overall length: 838 – 937 mm / 33" – 36.9"
Barrel length: 420 mm / 16.5"
Weight: 3.6 kg / 7.9 lbs empty
Rate of fire: rounds per minute
Magazine capacity: 30 rounds standard
The IAR – Infantry Automatic Rifle program was originally initiated by US Marine Corps (USMC) in an apparent intent to replace aging M249 SAW light machine guns in their "automatic rifle" (squad automatic) role. USMC sought lighter and more maneuverable weapon, still capable of at least some sustained firepower. Original contenders included guns from FN, Colt and Heckler-Koch, as well as some other, lesser known names. After extensive trials in 2009 USMC finally selected the HK IAR rifle, which, in fact, is no more that heavy-barreled version of their HK 416 automatic carbine (assault rifle), and it hardly looks like adequate replacement for a dedicated squad automatic weapon with belt feed and quick-change barrel. By all accounts, it looks like USMC played the whole IAR trick to get the replacement for their M4 carbines without entering the political hassle and budgetary debates. In May 2010 the USMC representative officially anounced the adoption of the Heckler-Koch IAR as M27 Infantry Automatic Rifle". It is not clear when HK will begin delivery of the M27 rifles, and how much rifles will be delivered to USMC.
The M27 Infantry Automatic Rifle is a gas-operated weapon which is based on the HK 416 assault rifle. It uses short-stroke gas piston that operates the 7-lug rotating bolt, and fires from closed bolt. Receiver is made from high grade aluminum alloy. Combination-type safety / fire selector allows for single shots and full automatic mode. M27 IAR retains all M16-style controls, including last round bolt hold-open device, rear-based charging handle and magazine release button on the right side of the magazine well. M27 IAR is fitted with four Picatinny rails as standard, and may accept any type of sighting devices on STANAG-1913 compliant mounts. Buttstock is of typical M4 design, multi-position telescoped. M27 Infantry Automatic Rifle can feed from standard M16-type 30 round magazines, and will also accept high-capacity double-drum magazines from Beta Co (100 rounds capacity) and Armatac (150 rounds capacity).