Pistol Grip Magazine Well, Predates Czech Sa Vz 23

Many of you may have heard of the Japanese Type 100, the Empire of the Rising Sun’s only fielded submachine gun. It was a blowback operated, magazine fed, bayonet mounted, 8mm Nambu submachine gun that was fielded too late in the war to make a difference, and wasn’t manufactured in significant quantities (under 30,000).


But before the Type 100, there was the Type II. The Type II was entered into the design competition for a submachine gun before World War Two began, in the mid 1930s. It was designed by Kijiro Nambu and there are at least two different variants that reached prototype stage or even production. The second one was developed during the War, and is covered very well by Ian over at Forgotten Weapons. However the prewar prototype, we have the pleasure of viewing directly here on TFB. The model in the pictures is a non-firing deactivated piece, but nonetheless is an original Type II. Owner and location wish to remain confidential, but the pictures are being posted with permission. The picture of the submachine gun as a whole is actually all over the internet in numerous places, but the other detailed shots of the submachine gun are being published here for the first time. From the photographer-

This is a pre-production Japanese nambu SMG. This is a prototype made for trials but was not selected for final production in favor of the type 100. this is a nambu type 8mm SMG that has a very unique gas system upon which it operates. for lack of a better term it is kind of like a motor in which a piston created compression through baffles and cycles the bolt mechanism. this SMG is serial number one and has a mix of parts on it that range in serial numbers. It is unknown if it was made of several different SMG of the same type when the others wore out, or if the parts were replaced over the trials and numbered in sequence for each time they were replaced. This one is a DEWAT and i had the pleasure of photographing it several years ago. the owner wishes to remain anonymous and i will respect their wishes. i think they told me the magazine held 33 rounds of 8mm nambu..

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The Type II falls along the lines of “Great and innovative idea, horrible implementation”, similar to the Reising submachine gun we covered last week. The magazine was inserted into the pistol grip, thus predating the Czech Sa Vz 23 (often considered to be the first submachine gun design to incorporate such a feature) by more than a decade. It initially had a 50 round magazine, which sounds absurd, but a number of early submachine guns featured similar magazines of ridiculous capacity and weight (50 round drum on Thompsons, snail drums on MP18s). The 8mm Nambu cartridge was also just not sufficient enough to work the blowback action of the Type II as well. The submachine gun had a system of springs and buffers in the receiver that corresponded with the bolt. Adjusting this system would also adjust the speed at which the bolt would be returning forward for firing the next round. Essentially a submachine gun with an adjustable rate of fire. Ian explains it in his post-

A unique feature of this and other early Japanese SMG designs is the use of an adjustable buffer assembly. As the bolt flies backwards after firing, it is caught by a piston connected to a compressed-air buffer in the rear of the receiver. As the bolt pushes backwards, air in the buffer can only escape through a small valve, which has multiple different sized holes which the shooter can select from. This allows the bolt velocity to be controlled, thus giving the shooter control over the gun’s rate of fire. Our reference book says the rate can be 500 or 600 rpm, but the original report says the buffer has five different holes to select from.

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Much Thanks to Jarrod M. for contributing to this post!


Infantry Marine, based in the Midwest. Specifically interested in small arms history, development, and usage within the MENA region and Central Asia. To that end, I run Silah Report, a website dedicated to analyzing small arms history and news out of MENA and Central Asia.

Please feel free to get in touch with me about something I can add to a post, an error I’ve made, or if you just want to talk guns. I can be reached at miles@tfb.tv


  • Isaac Newton

    I’m confused was the Type II gas piston operated or blowback?

    • Red McCloud

      Blowback, but the bolt compresses a piston that controls the rate of fire

  • Amplified Heat

    Why is it that Japanese arms makers never seemed to come up with decent ergonomic solutions on their own? This thing looks just as awkward as their old matchlocks. Also, given the poor wood so often used for their stocks, I have to believe the butt of this one would snap off immediately from that socket were it fielded.

    The airspring concept as well as general receiver layout seem to be borrowed from the Suomi. And there doesn’t appear to be a charging handle?

    • A bearded being from beyond ti


    • bluecheesedressing

      Is that large vertical tab on the left side view the charging handle? If so, the left side bizarre charging handle kinda reminds me of a Japanese type 97 MG. This thing looks like it’s from an alternate realty- which I guess pre-WWII Japan kinda was. It’s cool to actually see something on a gun-blog that you’ve never seen before, props to Miles and Jarrod.

    • ostiariusalpha

      Well, that’s Kijirō-chan for ya’! Other Japanese firearms designers created pretty reasonable weapons, but good ol’ Colonel Nambu always seemed to create his guns to potentially either kill, maim, or otherwise make uncomfortable anyone shooting them. Still, since he was the best in-house smallarms designer within the Army, his designs naturally always won.

      • DaveP.

        Well, when your entire culture is based around hitting people with swords, it’s just natural you’d want to discourage the use of firearms as much as you could.

  • Sianmink

    Well it wasn’t going to win any beauty contests.

    • A bearded being from beyond ti

      No kidding. It’s hideous!

    • bluecheesedressing

      And yet I can’t stop looking at it-

    • Martin M

      Zowzas! The ugly!

      Yet, I start thinking, “I wonder if I could build that?”

  • Rusty S.

    That’s some serious wabi-sabi right there…

  • Zachary marrs

    To be fair, even if they had mp-5’s at the start of the war, it wouldn’t have made a difference.

    A common theme with WW2 era SMG’s is that they severed in far fewer numbers, compared to their service rifle counterparts.

    Such an ugly gun. I’ll take 10.

    • Emfourty Gasmask

      I think the Russians were the only exception to this, they put those PPsH’s out there in massive numbers because they were cheap and easy to build

    • Blake

      In addition to the Russians, the Finns also relied heavily on SMGs during WWII, with great effect.

  • Kyle

    What the hell? Look at that pistol grip! Kijiro Nambu must have had either some massive truckasaurus hands or some freaky triply jointed wrists. Only way he could have possibly picked up his prototype and think was comfortable to carry around.

  • Rock Island Auction

    Fascinating! Thanks for sharing these photos.

  • Tinkerer

    Are we certain about the “Type II” nomenclature? As in, is it written in Roman numerals -so it reads as “Type Two”-, or in Arabic numerals -so it reads as “Type Eleven”-?
    I ask because it would be the first time I’ve seen Japanese usage of Roman numerals. Meanwhile, if it’s “Type Eleven”, that would fit with Japanese traditional nomenclature: “Made on the Eleventh Year of the Showa Era” -which would be 1936 or 1937.

    • ostiariusalpha

      In Japanese the gun is called the 試製二型機関短銃 (Shisei ni-gata kikan-tanjū), or “Experimental 2nd Model submachine gun.”

      • Tinkerer

        Ah, it was a transliteration thing. Got it.

        • ostiariusalpha

          Yep, just a quirky decision by the original translator.

    • jay

      I believe that’s Ereven.

  • TheNotoriousIUD

    War is hell but I truly pity any man shot with such an ugly a-s gun.

    • Giolli Joker

      And the problem is that with 8mm Nambu you have to be close enough that you see it…

      • TheNotoriousIUD

        Now thats a real war crime.

  • Swarf

    Maybe… maybe this was designed to be comfortable for some raptor-clawed tentacled hentai nightmare to fire and the war ended before the Japanese got to release them?

    Maybe we got lucky.

    • jay

      I was going to say something about Tentacles and Schoolgirls. But decided not to, as It might be in bad taste.

  • adverse4

    One ugly MFer. However, there is no rule that a firearm has to be pretty to kill you.

  • Tinkerer

    Wait! Is it just me, or is that entire perforated barrel shroud -complete with it’s integrated front sight- actually a reciprocating, telescoping bolt!?

  • iksnilol

    I think it looks cool, has a crude sci-fi punk look to it. Reminded me of Akira.

    • ostiariusalpha

      Reminds me more of what someone might think a Warhammer 40K Ork Slugga or Shoota would look like. Ramshackle.

  • B-Sabre

    So….what happens when the valve controlling the rate of fire gets fouled with mud and dirt, which is a frequent occurrence in jungle environments? You suddenly find your magazine emptying in a single trigger pull?

  • PK

    All of you commenting how hideous this SMG is haven’t looked into the many interwar and post-WWII prototypes while the now-accepted form was being hammered out, evidently.

    Here’s a “lovely” compilation (not to scale) of British prototypes, for example, ranging from 1938 to 1945:

    • Mr Saturday Night Special

      But none of these got into production, let alone consideration.

  • jeepers

    When I see a firearm that I have never even heard of, well, I’m impressed. Great article.

  • Zebra Dun

    BeJeebus! I’ve heard of Steampunk appearing fire arms but this looks just plain Klingon to me.

  • Mr Saturday Night Special

    Looks like a serious sand nightmare for combat.?

  • Old Vet

    It would seem with the fanaticism of the Japanese it is a good thing all their weapon system sucked. I have not seen one Japanese design I would care to shoot, collect, or even look at. This design begs interpretation for me. Their pistols were an accident waiting to happen, their bolt rifles were outdated when fielded……and on and on….

  • Reinhard

    Yep, sure is ugly. The design fits in with many other Japanese designs. This is certainly an interesting blog.. I used to train operatives in “obsolete” weaponry prior to their insertion to various destinations at Camp Peary. I never ever saw one of these or knew of their existence. In addition, all of my family ought in the Pacific. I thank whoever for this article. It was most informative.