Colt Infantry Automatic Rifle (IAR)

Steve Johnson
by Steve Johnson

The Colt IAR is Colt’s entry in the Marine IAR competition for a lightweight automatic rifle to replace the SAW in certain situations. It is an interesting weapon.

Photos by SMGLee. Click to expand

Under the barrel you can see a hefty heatsink. This is used to prevent cook-offs (when the primer of a chambered round is ignited by a hot chamber). It weights 9.5 lbs and has a 16″ barrel.

It looks like the barrel may be be changed by simply removing the bolt you can see just in front of the magazine well.

Surprisingly the rifle/machine gun does not use a gas piston and uses the AR-15/M16 direct gas impingement system.

The above photo does show a Magpul PMAG but the Marines have specified that the IAR must be compatible with 30 USGI magazines, so it is unlikely the military will be adopting PMAGs, even in a limited role with the IAR.

Other IAR entries can operate with either an open bolt, in automatic fire, or closed bolt in semi automatic mode. This allows the accuracy benefits of a closed bolt with the heat reduction and reduced chance of a cook off of a closed bolt. I am not sure if this weapon has this feature.

Colt already have a lightweight automatic rifle, the Colt Automatic Rifle (CAR), which itself may meet the Marines requirements. I do not know if the Colt IAR has anything in common with the CAR, other than the shared AR-15 heritage.

Colt Automatic Rifle

UPDATE: Defense Review has more info.

Steve Johnson
Steve Johnson

I founded TFB in 2007 and over 10 years worked tirelessly, with the help of my team, to build it up into the largest gun blog online. I retired as Editor in Chief in 2017. During my decade at TFB I was fortunate to work with the most amazing talented writers and genuinely good people!

More by Steve Johnson

Join the conversation
2 of 20 comments
  • Jacob Jacob on Apr 10, 2010

    look i am currently a saw gunner and i read a post or two about the amount of rounds trust me every saw gunner in the marine corp wants this weapon now while raiding a house a saw is not practical and with all are ppe we are not moneverable with the current weapon we can use 100 round mags

  • Bruno Bruno on Jan 31, 2011

    The Colt Automatic Rifle is a great MilSpec rifle, it just... don't do what it's was planned to do. But now with all the IAR talks, it was adopted (along with the newer Colt IAR - different guns) at some degree by the Mexican marines (it's possible to spot both in photos).
    Open-bolt, full auto capable without overheating, the magazine feeding kills it. But it has great accurracy in the closed-bolt variant made by Diemaco. It was shipped to Canadian Armed Forces together with the C7s and C8s in small numbers. The Canadians then gave them to a european country, and now it serves as a DSMR there.