Factory Colt 9MM SMG And Sub-Carbines

It is easy to forget that the Colt once experimented with many variations of the AR-15 platform. Over the years they made many attempts to develop what we would call today a PDW. TFB writer Ethan has cataloged every 9mm Colt SMG-style sub-carbine they developed over the years on his personal gun blog. He dug up a number that I had never seen before. I highly recommend checking them out.

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.


  • Masoo2

    I have known about the 9mm. Colt SMGs for a while, but that experimental model 633 (Pictured( actually looks very interesting. Ambi bolt release and safety selector, cool handguard made out of aluminium, what’s not to like?

  • claymore

    We had the Model RO635 select fire (auto not burst) as issued equipment since around 1985 in the Connecticut State Police SPTU (tactical team) team.

    They shot fine BUT there was one large problem that never was found by the selection committee that I was part of.

    We found out the hard way the UZI mags they came with if dropped on a hard
    surface would launch all the remaining rounds right out the feed lips in one continuous stream.

    After some experimentation we found that even slapping the mag into your open hand could cause this to happen.

    It turns out it was a faulty mag design by UZI. The feed lips were so far apart that anything that overcame the spring tension and friction would cause the rounds to fly out of the mag one right after another.

    We were pretty close to Colt and worked with them opening and closing the distance between the feed lips to try and solve this problem but never could.

    They lasted up until the early 90’s like this but were then replaced with MP-5s.

    If you have any UZI 9mm stick mags this effects them also.

  • hami

    I imagine the oversized shell deflector is for ambi use. You never know when you’ll have to switch shoulders in tight spaces i suppose.

    • claymore

      That may have been the thinking but in real world use the empty cases came straight out the ejection port flying at right angles right into whoever was on the line next to you never even touching that bump.

      And I found out the hard way shooting left handed close to a wall those same cases could and did bounce off the wall right back into the ejection port. The first time it happened was like WTF was that. until we took a closer look while firing from the same position and watched it happen again.

    • Vermin.308Winchester

      The military was pretty dam stiff about making everyone shoot from the right shoulder I don’t think they made any exceptions for cqb

  • Alex C.

    The 9mm Colt SMG is the smoothest shooting sub gun I have ever played with. I shot an MP5 and a Colt SMG back to back a few years ago at an MG shoot and the Colt surprised the hell out of me. Ergos and manual of arms of the AR platform with an equally crisp trigger (the HKs all have that long and mushy trigger). I swear I could have written my name with that gun!

    • Zeitgeist

      Then you are in a minority. I used SMG’s for many years, and never found a daily user who preferred the AR to the MP5. The heavy bolt creates a rocking that is not nearly so obvious on Semi, but becomes difficult to manage on FA. Frankly, I’d rather have an open bolt Uzi or PM12 than an AR, and the MP5 was better than those.

      Still, the AR was totally usable for its purpose, and that mag issue wasn’t really an operational problem even if it was not confidence inspiring. The AR was a fine working gun, but it was working in rarefied company by the time it was introduced. Compalints are kind of splitting hairs.

      • claymore

        LOL you think all your rounds flying out of any mag is “splitting hairs?

        • Zeitgeist

          Well, in this context I stand by what I said. During the sort of fight you bring an SMG to, you aren’t going to stop to pick up a dropped mag until it’s all over anyway. I’ve never had a mag eject rounds when being seated, which is a total game stopper and should be enough to disqual the system if it was a more than lightening strike frequent issue. Like I said, rounds falling out of the mag when dropped isn’t confidence inspiring, and it is a pain in training sometimes, but not a fatal flaw. The guns we had came from a federal agency and were practically new having been sitting unused in a DC armory for years, so maybe the mags were still tight enough it wasn’t yet a problem for us.

          The bolt in the AR is not as centrally placed for balance as the just over the strong hand UZI’s is and so the rocking is felt during the entire cycle, not just at firing. That is nit picking, though, and subjective. Of course, I can use an open bolt SMG with safety, but I am not responsible for teaching a large group to do the same thing so our priorities may be legitimately different. I also consider a BHO a nice to have but not mandatory feature in a long gun. I’ve seen way too many well trained people miss that cue in training, let alone in actual combat, to trust it to tell me when it is empty. We switched from the MP5 to the MP5/40 for several months before I left LE SWAT to go international, and the BHO did not change how we used the gun at all.

          • claymore

            It IS a problem if it’s your last fresh mag LOL. And as police our basic load carried is minimal as we normally don’t get into long lasting firefights so the loss of maybe your only reload is very important.

            The bolt forward of the pistol grip actually helps hold the muzzle down as the rotation point is your hand making it ever so slightly nose heavy which aides in holding the muzzle down.

            Firing from a closed bolt eliminates the need for a sometimes not applied enough grip safety (real bad when one goes to fire and it doesn’t) and extra parts need in the cover to prevent a runaway bolt reducing unnecessary mechanisms.

            A BHO is good for a couple of reasons the first being it speeds up mag changes, second it makes clearing malfunctions so much easier, and third it makes identifying a “cleared weapon” into a simple glance.

            We could go on for days “discussing” the difference in subguns as it has been done since their inception the bottom line is it comes down to the preferences of the operator.

            We did change to the MP40 for this problem and to use a matching our handgun caliber.

      • claymore

        The “heavy Bolt” is not a problem while firing even in auto mode since it fires from a closed bolt and it’s a safer firearm because of closed bolt firing.

        Much more easy to keep on target than an open bolt firing UZI. And yes I have fired both type of systems side by side extensively during our selection process.

        The MP type was rejected for no last round bolt hold open

  • Samuel Suggs

    are their an on the transferable market