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 [email protected]