Mystery Japanese Semiauto

While in the Smithsonian gun room, I noticed a semi auto Japanese rifle of a type I have not seen reference to before. It is definitely Japanese, judging from elements like the split buttstock and rear sight, and the ventilated underside of the hand guard is reminiscent of the Japanese Pedersen rifles. However, this rifle uses a rotating bolt and a receiver design that I am not familiar with.

Has anyone seen this before? The tag on it said it was a Type 5, which believe was a mix-up with the rifle next to it on the rack (which was a Type 5 Japanese copy of an M1). Click on the photos to enlarge:

Ventilation on the underside
Ventilation on the underside
Magazine floor plate
Magazine floor plate
Top of the action
Top of the action


  1. I see a lot of small parts that are reminiscent of the Arisaka bolt action rifle. Re: rear sight, front sight, configuration of the trigger guard, and the way that the floor plate is latched. I’m sure they were developing a semi-auto, as the bolt action rifle….against the M1 Garand….was a losing proposition.

  2. According to W.H.B. Smith & Joseph E. Smith in The Book of Rifles (1964 ed.);

    In 1904 Japanese Artillery Major Nambu and Infantry Captain Hino tested an automatic rifle before the Emperor, a description of the tests being given in issues of the German “Militar-Wochenblatt” of that year. The rifle was unsuccessful, but out of the experiments came the Japanese Nambu light machine gun.

    -Smith, p.69

    The latter statement may be a bit off, as the Nambu LMG was of course based on the French Hotchkiss system. But the rifle could have been a parallel development also based on that system.

    Captain Hino was I believe the same man who was involved in the Hino-Komuru blow-forward pistol design.

    Is it possible that this rifle is the 1904 Nambu/Hino test article, or one similar to it?



  3. This wouldn’t be one of those Japanese “Garands” would it? IE one of the semiauto rifles that were copies of our service gun.

  4. It almost looks like some one took parts from an Ariska, a Type 5, a Pederson and a few others and had an open mike night at the smithing table…I am now very curious.

  5. sadly there no picture that show the rifle complete
    but looking at muzzle and Ventilation on the underside
    I think that is a Model 99 rifle, there were two derivates, one for Snipers and for Paratroopers
    either one of two could be that rifle on Photo

  6. Looking forward to hearing about this when you figure it out! ^__^

    Have you found a catalog entry for it anywhere? I bet there are quite a few lost treasures in there!

  7. It must be a modified experimental Kokura Rifle.Some prototypes were made by Kokura Arsenal during the Pacific War but they never went into production.By the way,the Kokura Arsenal was also the manufacturer of the unique experimental toggle lock Type A rifle which was made before the Second Sino-Japanese War.

  8. The rifle is shown in an article “Japanese Rifles and Carbines” by M.D. Waite from American Rifleman, February issue of 1958. The author states that it is a locked-breech recoil-operated semi-automatic rifle that uses 7.7mm rimless cartridge, it feeds from 5-round box magazine and has a mounting bracket for a Japanese 2.5x scope (the one used on Type 97). Also there is a picture of the rifle’s stock being hinged down from barrel/action group (in similar way to ZH-29).

  9. This is one page 169 of Honeycutts military rifles of Japan 5th edition. Its listed as variation of Rifle plan #1 by kokura arsenal 7.7mm for army evaluation during 1941-1943.

  10. The expertese and scholarship that can be brought to bear by Ian’s readership never ceases to amaze me. Well done!

  11. From the close-up of the Action it looks like one of Mauser’s 1906-08 Auto Rifles; but the Muzzle fitting could be either a “Gas trap” (Bang system) or a straight recoil system. Only a complete strip-down and examination will determine which design (or designs) Kokura put together for this Prototype.

    Doc AV

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