Colt Infantry Automatic Rifle (IAR)

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.

 Smglee Ausa Huge Dscn0965

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

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • jdun

    The quick change barrel IMO will be in the next generation AR design. If what you said is correct then the Colt IR is the prototype of it.

    The US military like DI because of it superior accuracy. No other action in automatic form is capable of equal or better accuracy then bolt action rifles.

  • michael

    That is one great looking carbine. The AR-15 Rifle had some shaking beginings during Vietnam but the evolution of this great weapon system must be respected.

  • Anchando

    This is definitely an awesome weapon. The only thing soldiers might miss is the ammo capacity of the S.A.W.

  • Terri Mathews

    Hey there!
    I was noticing that the government awarded a multiple contract for the IAR. Four contracts were awarded but my source has two of the companies as Colt! No way- that can’t be right. You seem to know all about firearms, do you know who the fourth company was? The other three were Colt, FN Herstal, and Heckler&Koch Defense.

    Can you help me out????

  • Terri,
    It may be the General Dynamics entry,the Ultimax.It is listed in one of the articles above.

  • IMHO the FN entry is going to be hard to beat.The H&K is a really good gun,but I think that FN may be more on target.

  • Jim

    The other was the LWRC


    I have shot this weapon while i was in the Corps. It is a nice replacement, and i was a SAW gunner. It is accurate, and easy to move around for any application that you use it for. I think this would do well for CQB as well for patrols, and other low drag type of missions. Doesn’t jam unlike a belt feed weapon but it will have its moments when it will trap brass. The only thing i dont like about it is how fast it blows off a mag.

  • Brig Gen Brogan USMC is quoted “IAR second phase competitive source selection was completed in December 2008. The field is down to 4; 2 from Colt, 1 from FN and 1 from H&K.” “the IAR is not a replacement for the SAW. The SAW is a great weapon, but it is a light machine gun, not an automatic rifle”

  • For a good understanding of the differnt application of M4, IAR and SAW check out “modern weapons”

  • Steve

    Nice, but I like the HK and FN entries better. The HK is my favorite.

  • Caduceus

    Nice, but I like the HK and FN entries better. I like the HK entry best.

  • Daniel

    TBH, the idea that DI gives superior accuracy is somewhat flawed, it’s more the calibre and the balistics of the round that contributes to it’s accuracy. I’ve personally fired the GD Ultimax and I can safely say it’s as accurate or even more so than my M-4, impression wise, I’d say the “kick” is about half to 1/4 that of a M-4/16 platform, and IIRC, that’s a short-stroke system. I suspect the DI was used in the 14/16 series as it was a new design in weapons and the designers errored on the side of safety when it came to the recoil/feed mechanism.

  • XxleoxX

    the weapon is beautiful. I’ve never shot it but i would probably get it

  • pocketsnzl

    The IAR uses the same general cooling system as the ‘kriss’ SMG and does not jam easily. This is also another feature of the ‘kriss’ as thes are of the same manufacturer. watch this video and see how revolutionary these rrifles and SMG’s will be

  • spencer

    this just seems dumb, I remember future weapons showcasing LWRC’s IAR and how i thought it was the dumbest thing ever. take away a 200rnd belt and trade it for a 30 round mag or 100 round drum? dumb, ive never used the saw, but i have the m60 e3 and love it, i know spray and pray isnt the answer but getting all of those rounds on target and down range in a hurry to break contact, provide cover etc is vital, now you have a guy constantly changing out mags? dumb, seems like a recurring trend of passing over the best option to later address it down the road, army’s failure to choose multicam and now looking to use it? dumb, stop wasting taxpayer dollars, buy the best and be done.

  • Colt really messed up, when they choose not incorporate the gas piston system like LWRC, HK, Knight, Bushmaster, Smith and Wesson, just to name a few. Colt may have made the M1911 .45 but they failed to learn from the Vietnam War with the M-16.

    • Core

      They do have a piston option. It’s just that gas works fine so why add the additional weight? I have had a fare share of failures from piston guns that were not maintained or built properly. The rate of fire is also effected by the gas piston. This IAR platform is intended for fire rates up to 1000 rds a minute. There are also high cap magazines available up to 100 rds.

  • 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

  • Travis

    Slightly off topic from the IAR, is that M4-ish carbine beneath it in the first pic a piston or DI gun?

  • Bruno

    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.