The Original Piston AR-15: 1969’s Colt 703

After the Ichord report of 1967 identified the early failures of the M16 rifle in combat, particularly failures to extract, solutions to the problem of fouling were investigated by Colt, as well as Rock Island Arsenal (a government entity), and Olin/Winchester. Colt’s effort was the 703, which they somewhat presumptuously offered to the Army as the “M16A2” in 1969. The 703 was not only one of the first – if not the first op-rod AR-15s, it was also the first “hybrid” AK/AR-15 design, utilizing a very AK-esque gas block and fixed flexible piston:

2015-02-08 16_02_00-The Black Rifle I M16 Retrospective (Better Copy).pdf - Adobe Reader

The disassembled Colt 703/”M16A2″. Note the gas block and piston, both of which greatly resemble that of an AK. Also of note is the different bolt stem design, and the enlarged cam pin, charging handle, and cam pin bulge on the upper receiver. This design added almost half a pound of weight versus the M16A1. Image source: The Black Rifle, Edward Ezell, R. Blake Stevens.

The 703 did not just modify the gas system, it also incorporated changes to the fire control (adding a fourth position for burst fire), bolt, handguard retention system (eliminating the frustrating delta ring design), and adding a cleaning kit trap in the buttstock – a feature quickly incorporated into the production M16A1.

2015-02-08 16_24_29-The Black Rifle I M16 Retrospective (Better Copy).pdf - Adobe Reader

The Colt 702/”M16A2″. To add to the confusion, the export variants of the later M16A2 second-generation US Army AR-15 were also referred to as the “Colt 703”. Image source: The Black Rifle, Edward Ezell, R. Blake Stevens.

As the propellant issues of the M16 family shook out, the need for the 703 evaporated, and the M16A1 continued in service with the Army until its replacement by the M16A2. Two Colt 703s still exist today, in Reed Knight’s collection.

Aftermath Gun Club has some more information about the Colt 703 on their website, including a full spec sheet.

Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He is also the author of the original web serial Heartblood, which is being updated and edited regularly. He can be reached via email at


  • john

    Ah, ’tis the story of Beta Max, a better product, yet not adopted for whatever stupid reasons they had. You gotta love it.

    • I’ve seen no record of it being trialled, so I have no idea if it was better or not. It certainly wasn’t lighter.

      • M

        6.9 lbs for a 20″ AR/AK hybrid is actually not too bad considering that the ARAK-21 is 7.6 lbs at it’s lightest (12.5″, medium profile barrel)

        • I can’t confirm the ARAK-21 weight numbers; we have a resident ARAK-21 expert. However, the ARAK-21 is unnecessarily heavy in my opinion. I agree that the Colt 703 is a good example of how and why.

  • gunsandrockets

    It’s Stonerriffic! Look at that rear sight, the 702 is like the bastard child of the Stoner 63 and M16.

    • It does look kind of like a Stoner 63 and an AR-15 had a baby, doesn’t it?

    • Gern Blanston

      thats exactly what I was thinking lol

    • n0truscotsman

      I like it. I wish that more companies would have made more piston ARs like this rather than short stroke ones, but thats just my opinion.

  • David

    How does Reed Knight get all the good stuff?

    • Being a personal friend and colleague of Eugene Stoner helps.

    • Raven

      IIRC, when he left Colt (after the All-American 2000 debacle?), there was something of a cash issue, so he cleaned out a lot of their rare prototypes as payment. Don’t remember where I heard that, it might be bullshit.

      • KAC/KMC did a lot of contract work for Colt including the integrally suppressed RO656 uppers, the muzzle brake for the ACR, and the AA2000. Knight himself has told the story of cleaning out Colt’s prototype room.

  • Isaac Newton

    Notice the tail of the carrier looks to be designed to help prevent tilt. Its amazing that even today some manufacturers brag about that design feature like they invented it.

    • I noticed that feature, but wasn’t confident that’s actually what it was designed to do.

  • idahoguy101

    Armalite engineers had the last laugh. The AR18 gas piston and bolt has been adopted by the G36, the SA80, the K2, et al… Without Colt making any money off it.

    • gunsandrockets

      I wouldn’t go that far. Clearly the AR-15 family is doing quite well in terms of international sales, even if it isn’t Colt necessarily making the money off of those sales.

      However it is interesting that the AR-18 is lighter than the 702, even though the AR-18 also has a folding stock.

    • n0truscotsman

      Sales wise, though, none of them have held a candle to M16s/M4s.

    • M

      Do they make money off of those designs or are you just saying Colt simply made less money?

      If anything it says they have a poor business strategy to let two major influential designs slip them by

      • Raven

        Colt never made a cent off the AR-18. The AR-15 design was sold to them in between Armalite developing it and the Army adopting it, but the AR-18 was owned by Armalite (and produced under license by Sterling and a Dutch company).

        • It was made here in California (Costa Mesa), by Sterling in the UK, and by Howa in Japan, The Dutch were never involved with the AR18. You might be thinking of AI making some AR10 stuff.

          • Raven

            I forgot about Howa! And you’re half-right about the Dutch bit. Nederlandsche Wapen-en Munitiefabriek were granted a license to build AR18s, but it seems like they never actually built any.

        • Wetcoaster

          I think he means that Armalite also didn’t make any money from the AR-18 derivatives, probably because they were designed long after the original design or aren’t clones to the degree where Armalite could claim patent infringement (if their patents were even valid in those respective countries by the 80’s)

          The AR-18’s sales were always miniscule to the point where I suspect it might have been a money-losing proposition considering the tooling involved. Quite possibly the same thing that’s going to happen with the Remington ACR

          • Tom

            The idea behind the AR18 as I understand it was that it could be made with primitive machinery. The problem was that by the time it came out the Soviets were handing out AKs like confetti and the Americans were not far behind with M16s. Those nations which truly cared about making their own weapons were quite capable of making M16s or making their own variants of the AR18 but with sufficient changes to prevent Armalite claiming royalties. More than anything else economics killed the AR18 though looking at current rifle designs it would be fair to say it got the last laugh with no “new” DI rifles coming to market.

          • I should think it is more flattering if someone copies your rifle wholesale, as has been done extensively with the AR-15, than if they only copy a few elements from it.

          • Wetcoaster

            No, the idea behind the AR18 was that it would be cheaper to make than the AR15 – stamped instead of forged and machined receivers, for example – the same transition made from the AK-47 to AKM.

            Stamped also means considerable initial capital outlay for the machinery in exchange for lower per-unit cost, but that only gets made up with sufficient volume (say HK G3s) which is why I wonder if Armalite didn’t actually end up taking a loss on AR-18 production.

    • Joshua

      Armalite engineers? You mean Gene Stoner who made the AR-16, the 308 version of the AR-18.

    • Wetcoaster

      Unfortunately, I think the engineers who had the last laugh were the ones who worked for neither Armalite nor Colt.

      You can also add the Singapore SR-88 to that list and probably the Taiwanese T86/T91

    • MichaelZWilliamson

      Everyone else had the last laugh, as Armalite sold all its designs right before they caught on and made money for someone else.

  • Broz

    Looks like an AR 180 upper on an AR-15 lower…

  • Caffeinated

    Looks like the Taiwanese Type 65 rifle. Funny how what is old is once new again!

    • McThag

      Well, the Taiwanese T-65 looks like the R703, and not by accident.

      • Caffeinated

        I’m glad someone took the design and ran with it. I find it kind of funny that so many people have jumped on this piston fad in the last few years and decided to reinvent the wheel sort to speak.

      • The T65 is not closely related to the 703, having a short-stroke piston design essentially copied from the AR-18.

    • Pete Sheppard

      I thought of the S. Korean Daewoo rifle.

      • Caffeinated

        The Daewoo uses more of an AK based bolt carrier and recoil spring assembly whereas the T65 is one of the earliest forms of the piston AR.

        • Pete Sheppard

          Thanks. I figured there were other changes, but the overall appearance triggered the thought. Form follows function and all that. 🙂

          • Caffeinated

            Sure wish they would re-import the DR rifles especially at the old <$400 price.

          • Pete Sheppard

            You and me both. Long ago, Chuck Taylor wrote a very nice review of the rifle. It sounded as if it was an excellent alternative to the AR

          • Caffeinated

            Yeah I got to play with one in my earlier years and it was a little rough along the edges but seemed to be AK reliable with the ergonomic controls of the AR platform.

          • Pete Sheppard

            I actually got to handle a mid-’90s model with the AWB thumbhole stock.

  • Marc

    Looks like the piston could swivel around the pin that connects it to the bolt carrier. I think a more rigid connection would be preferable.

    • Rigidity causes binding; that’s why the AK also has a flexible piston.

  • Uniform223

    I heard about this rifle a few times. Did it also have issues with carrier tilt?

    • I don’t know that anyone still living knows.

  • claymore

    The M-16’s we fam fired in the USMC in 1969 had the 4 position selector installed. Burst and automatic and it had an engraved plate in red showing the positions covering the normal ones built into the receiver. Never could get a look under that plate to see if they were marked normally underneath.

  • Andrey Martim

    I have a question, and English is my second language, so help me…

    That rear sight “guards” that look a lot like the ones on the Stoner, the Uzi and the Thompson pre-wa models… Even the AR-15 have some that looks like it in the carrying handle… What is the purpose of these things? It really is a guard or… i just can’t find a purpose for two more pieces of metal on the gun.

    • It just protects the rear sight from damage or being bumped out of adjustment. Simpler rear sight designs, like those on the AK or FAL, do not really need protection as they have minimal adjustment anyway.

      Now, why the M1 Thompson had those protective wings too, I have no bloody idea.

      • Andrey Martim

        Thanks man!

      • Tom

        No experience here so just speculating but could the posts be used as some sort of crude gutter sight for close work ie. room clearance.

        • In a couple of cases it was advertised as such, but in general I’m not sure if it was considered useful for that purpose.

  • Bob

    Reckon if someone made a copy of that it’d sell quite well commercially…

  • Zebra Dun

    It all started when they didn’t put a gun on the F4F Phantom Jet.