Weird Magazines, Vol. III: The Heckler & Koch Transverse SMG I Mag

In the early 1980s, German gunmaker Heckler & Koch began to design a new submachine gun that would improve on the existing MP5, in response to a US Navy solicitation for an advanced submachine gun as part of the Joint Services Small Arms Program (JSSAP). The SMG I, which was the product of this development, is not the focus of this article, so instead I’ll refer readers to the HKPro article on the weapon:

Not a tremendous amount of information is available about the submachine guns that were designed and built in the 1980s as attempts to improve the MP5. The SMG I, the SMG II, MP2000 and MP5-PIP are designs that became functioning firearms, but never reached full production status. All but the MP5-PIP and the MP2000 included a valve that was just forward of the magazine for the selection of super or subsonic ammunition. All of these prototypes with the exception of the MP5-PIP were designed with integral suppressors. The SMG I and II are covered here.
The SMG I was designed in 1981 for the United States Navy under the JSSAP (Joint Services Small Arms Program) Advanced 9mm Submachine Gun program.

The magazine in question was developed around the same time as the SMG and its HK54A1 stablemate, and was a transversely mounted 30 round 9mm drum. An article by Jim Schatz for Small Arms Review mentions a drum and its association with the earlier HK54A1, but fortunately we also can read the original H&K proposal, also available through that website:

The proposed drum magazine shall have a capacity of not less than 30 cartridges. The proposed magazine viewing apertures arranged at 10-round intervals shall indicate loaded conditions. The proposed magazine shall conform with performance requirements.


The HK SMG (later SMG I), with transverse 30 round drum.


The drum magazine for the SMG I was as one might expect not compact enough to justify the additional weight, complexity, and cost versus a traditional 30 round stick-type magazine, and as a result its development appears to have been dropped early in the project.

2015-10-27 15_00_38-The Missing Link_ Heckler & Koch's _Family_ Submachine Gun


H/Ts to Maxim Popenker and Daniel Watters

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


  • ostiariusalpha

    Ah, HK and their 80’s space magic. Was there anything more possibly rad than being armed with a SMG I, having a G11 slung over your back, and a P7 as your backup pistol? I think not.

    • Doing it WHILE wearing a Nintendo Power Glove.

      • ostiariusalpha

        It’s so BAD!

      • Tassiebush

        And Reebok Pumps

        • Griz

          Reebok pumps were popular in the 90’s, they were only released 1 month before the end of the 80’s (Nov. 89)

          • Tassiebush

            Damn fallible childhood memory

          • MR

            Gleaming white Adidas kicks? Maybe with the velcro straps?

      • Anonymoose

        Now for the ride- red Countache or gold-plated DeLorean?

        • iksnilol

          Ferrari Testarossa.

          Best ride to die in and return 30 years later as a superpowered zombie.

          • Marshall

            Kavinsky? Awesome.

          • iksnilol

            Aw yiss.

      • tts

        Don’t forget to put the slap bracelets on over the Power Glove first though!

      • Nergyl

        I can practically hear the synth pop blaring.

      • Come on, you can’t accessorize without going for a complete look. A single glove will not save you from sucking. Only a fully decked-out cyberpunk kit will ensure that nothing will clash.

        • JK

          “A single glove will not save you from sucking.” See “Thriller” era Micheal Jackson.

  • Matthew Groom

    While it would obviously be more compact when loaded, it would certainly be awkward to carry spares. Also, if you think HK mags are expensive now, just imagine how expensive those things would be.

    • ostiariusalpha

      The spares would be standard mags, though the SMG I was more design for situations that were going to largely be resolved one way or the other on the first mag.

    • Anonymoose

      Looks like it would be a little thicker than 2 STANAG mags, and much shorter. They’d certainly make pouches for it if they ever manufactured this drum.

  • DW


  • hkryan

    Cool looking but why the bulky 1200 m rear sight on an SMG?

    • ostiariusalpha

      Just a lil’ of the ol’ razz-a-ma-tazz to impress all the rubes with purse strings.

      • JSmath

        I appreciate the references made in your comment.

    • Anonymoose

      Why the heck not? Don’t Lugers and Inglis Hi-Powers have 1000m leaf sights?

      • iksnilol

        Gotta respect the beaten zone that a Luger with a snail drum provides.

    • If I remember correctly, the sight was modified so that it could compensate for the separate trajectories of supersonic and subsonic ammunition.

      • ostiariusalpha

        Yeah, but they figured they could do that just the same with the old MP5 style sights, which HK went back to on the SMG II.

  • mechamaster

    The magazine looks like Tony Stark Arc Reactor. Or something like phased plasma rifle battery… Must be fun for sci-fi prop. ( just kidding )

  • Mark

    F’ing sweet

  • MR

    Okay, my buddies tell me HK doesn’t think we suck, and doesn’t hate us. Still, I want an “HK-You Suck and We Hate You” polo shirt. I normally wear Ts, but HK just seems like they deserve classier treatment than that.

  • NukeItFromOrbit

    Love these articles on strange magazines. Not too long ago I remembered reading mention of a “self-powered magazine” tested alongside a conventional spring-loaded magazine as part of LSAT carbine development. Yet I’ve not been able to dig up any details. Would you happen to know more?

  • Anomanom

    If you squint, you can kind of see the beginnings of the MP7 in the upper frame.

  • This goes to show that retro-futurism is NOT just the 30’s-40’s amazing stories magazines and world fairs. It’s also real, functioning things from as close as 30 years ago. The former glimpses of the future always hold something that is lost, a little, in the slow transition to the actual future. And this something can be not lost, but found again, and inspire people.

  • gregge

    Will there be a weird magazines article on Calico Arms?