RIA: Japanese Army Pedersen Copy Trials Rifle

The Japanese military was interested in finding a new self-loading rifle to adopt in the 1930s. The development project began with a request to retired General Kijiro Nambu who designed a gas-operate,d rotating bolt rifle but could not bring it up to the standards demanded by the military and opted to abandon the project in favor of a new light machine gun (which would become the Type 96 Nambu). Two major commercial firms entered the fray, Nippon Special Steel with a gas-operated and toggle-locked rifle and Tokyo Gas & Electric with a copy of the Czech ZH29 rifle. In 1933 the Army itself decided to jump in as well, developing a delayed blowback Pedersen copy at the Koishikawa Arsenal.

The Army rifle was pretty good, but apparently never overcame extraction problems which would appear when the rifle became hot from sustained fire. When John Pedersen had demonstrated his rifle in Japan, it seems he did not mention the necessity for lubricated ammunition and this trick was not figured out by Koishikawa personnel. The Army liked the mechanical simplicity of the delayed blowback system (which required no gas ports, pistons, tubes, or anything else), and opted to fit the rifles with 10-round rotary magazines.

After the final set of trials in 1937, the whole semiautomatic rifle program was dropped, as the escalating war in China shifted priorities to producing a large number of less expensive and readily available Arisaka bolt actions.


  1. The Mannlicher–Schönauer, was adopted in 1903 by Greece, chambered for 6.5x54mm MS (.452 head size).

    There was also precedent for rotary magazines from Savage’s 1899 – which IIRC, Savage had hoped to attract military orders for, Just as Browning and Winchester had for the box magazine Winchester 1895.

    Both the Schönauer and the Savage magazines required the rotating spindle and the magazine casing and feed lips to be matched to the particular round that was to be used. Greek 1903 M-S rifles were therefore not popular targets for Bubbaficating, when they were available on the surplus market.

    With the Savage 1899, It appears that during one of the liquidations or at least changes of ownership of the Savage name and designs, the tooling and probably the skills and dimensions for the various mag spindles were lost (sold, scrapped, fired, whatever).

    I’m not very well up on savage ’99s, so please be aware that some of what follows may be incorrect – I gather that some were manufactured with incorrect spindles and did not work as they should have. The most recent 99s have box mags, as followers and feed lips are much easier to adjust for correct feeding compared to a rotary mag – or at least, the knowledge of how to adjust them for correct feeding is more widely available

    Regarding Pederson’s wax coating for cartridges, he applied for a British patent (British patents would only be issued if the British patent was the first one to be applied for) on March 20th 1928, the Patent was granted as number 304,948 on January 31st 1929.

    Clearly (and unlike the ridiculous assumptions of “perfect knowledge” which are routinely made in mathematical economics) the Japanese designers could not have been expected to have knowledge of the patent.

    (and neither did WWii British and American intelligence have knowledge of the British patents of both the German enigma machines, and the fuel injection systems for German aero engines).

    • “Both the Schönauer and the Savage magazines required the rotating spindle and the magazine casing and feed lips to be matched to the particular round that was to be used.”
      On the other hand, considering from Savage Model 99 and Mannlicher-Schönauer (hunting versions) when done properly it can fed wide array of cartridges. Before 1st World War following cartridge (except 6,5×54) were available:
      9×56 (Modell 1905)
      8×56 (Modell 1908)
      9,5×57 (Modell 1910)
      all cartridge were named Mannlicher-Schönauer, names in brackets are for rifles. After its introduction 6,5mm version stayed most popular.
      In 1920s enlarged version, able to handle bigger cartridges was developed – this version was called Modell 1924, it was available for following cartridges:
      8x57I (not to be confused with 8x57IS)
      8×60 S (cartridge created in Germany shortly after WW1 for hunters as substitute 7,9×57 which was banned by Treaty of Versailles)
      10,75×68 (German cartridge can be fitted in Standard size Mauser Gewehr, crafted for hunting in Africa, photo – http://www.deutsches-jagd-lexikon.de/index.php/10,75×68 )
      After 2nd World War new version was developed – Modell 1950 and Modell 1952 these can be found in wide variety of cartridges, which include, but are not restricted to:
      6,5×54 – 6,5×55 – 6,5×57 – 6,5×68 – 8x57IS – 8×60 S – 7×57 – 7×64 – 9,3×62 – 9,3×64 – .30-06 – .270 Win – .257 Roberts – .243 Win
      Production ended in 1972, but nonetheless Mannlicher-Schönauer is still used and well-praised by Austrian hunters.

      • The mention of the Greek M1903 rifle was to show that the M-S had seen military use (however insignificant) rather than simply use in high priced sporting rifles.

        The M-S sporting rifles were all factory made in those calibers, with the magazine innards specifically tailored to each individual chambering.

        Their existence does not detract from the fact that the central spindle needed to be formed to hold each individual cartridge with a slight gap between it and its neighbours, and to present each one individually at the correct angle to be fed

        and that likewise, the casing within which that spindle rotated, needed to be sized appropriately.

        Done correctly, the Schönauer and Savage magazines can give very certain and smooth control over cartridge feed.

        however, any changes in cartridge dimensions require changes to be made to the spindle and the magazine casing to ensure reliable feeding.

        The inability of both Post WWii Bubba to get M-S rifles to work as repeaters with anything other than the original 6.5x54mm cases,

        and the inability of later owners of the Savage name to get rotary magazines to work reliably

        Illustrates that such magazines are a much more difficult proposition to “get right” than a Lee style Box magazine is.

      • Sorry Daweo,
        I guess we were both saying broadly the same thing.

        Mny thanks for the contribitions about the calibres that the genuine M-S sporters were made in

    • A comment by John D, in the Arthur W Savage biography, regarding the problems with the Savage 99 magazine spindle/rotor.


      Jacob –

      The magazine spool (rotor) in the Model 99 is caliber specific and very tricky to manufacture. Savage lost and/or damaged the spool tooling and gauging during their long, bitter 1988 bankruptcy and no one has figured out how to make the spools again. A reformed Savage Arms made 1,000 Model 99’s in the 1990’s from Spanish investment castings, but they had to use box magazines due to the spool issue. American shooters were never very enthusiastic about the box magazine Model 99s and the ‘Spanish’ Model 99s did not sell well.

  2. Forgot to say

    Giovanni Agnelli’s was issued British patent 8943 of 1915* for fluted chambers. This had not found favour with the wooden headed military bureaucracy who considered oiling cases to be a well proven and reliable practice.

    At that point Agnelli’s idea appears to have left to take a long vacation down the memory hole.

    The Japanese forces went on to do some excellent work on Becker-Oerlikon type advance primer ignition blow back cannon for aircraft use – but I’m unsure of the timescale. Those cannon definitely required lubricated cases.

    I’ll be posting the number of Agnelli’s patent for a rotary bolt for delayed blowback use (Villar Perosa type) in the Thompson Rifle thread.
    it’s GB191330077A

    * at that time, the numbers started again at patent number one each year, so the full number for anyone who wants to look it up on espacenet is GB191508943A )

  3. Incidentally, that’s a lovely piece of walnut and beautiful finishing for a Japanese rifle.

    I bet that they were a pleasure to fire, chambered in 6.5x50mm.

    Thinking about the close similarity in case dimensions between Japanese and Greek 6.5mm rounds (76.00mm and 75.69mm overall loaded length respectively and the same head case diameters)

    It may not have been a particularly difficult task to adapt the Mannlicher–Schönauer magazine design to feed the Japanese round reliably.

    The Japanese military had also had contacts with the Italian Arsenals/manufacturers. Breda, for one, had certainly manufactured M-S military rifles for the kingdom of Greece.

  4. Toggle engagements seem rather different than Pedersen’s. It looks as if Japans reinvented whole construction from the beginning to end.

    • It seems that, Japans ingeniously simplified Pedersen’s complicated multi axis system. Pedersen delay action bases upon superimposed front joint and uses the middle joint for following slow down. Japanese example seems using only middle joint and the gained momentum of moving toggle elements. This requires a strong influence into the novel action and deserves admiring as much as the original concept gets.

      It also appears that as if some parts relating firing pin with connections are missing.

      • And it appears one could rebuff the old conservatives in the US Army Ordnance Board who claimed that the Japanese were nothing more than worthless copycats. Making the action simpler on the Pedersen makes manufacturing a bit easier when it comes to machining the parts at finishing. A fluted chamber would have helped with extraction without requiring oil or wax, but how would one flute the chamber and test it to be sure casings weren’t torn by uneven shear stresses with the chamber surfaces? Perhaps the Nippon Special Steel Rifle would be a better choice for actual combat…

        Speaking of weird stuff going on whenever Japan gets its hands on Western tech and finds new uses for the application, one has to wonder why the Ho-5 auto-cannon was emulated in American service and then improved (let’s get it to chamber a more powerful cartridge and increase service life and production quality) during the Cold War, since the design was based off the Browning M2, about which nobody complained.

        Why China has to start complaining about the helicopter carrier Izumo, I will never know (sarcasm here). Izumo is probably as big as IJN Kaga, if not bigger, but her deck plates can’t handle the heat stresses associated with turbojet exhaust, such as that from the F-35 Lightning II, and with no ski jump or catapult, forget launching attack planes of any kind. The most advanced Japanese warplanes that could launch from Izumo as she is today would be the Mitsubishi A6M5 Zero, the Aichi B7A Ryusei, and the Yokosuka D4Y Suisei, none of which are in production today, and none of which could actually do any realistic damage to Chinese property due to getting shredded by the PLAAF before they even got to cruising altitude. As a result, Izumo can’t really go to war unless she’s sic’ing ASW helicopters on North Korean submarines. Without escort destroyers, Izumo is just a big target. So shut up, Chinese Communist Party stooges!

        Did I mess up anything?

      • May be said, this rifle is definetely, not a copy but a respectable improvement over Pedersen’s concept.

        Pedersen’s toggle, at instant of firing, has its middle joint slightly over the line joining the front and rear joints, as giving an ability to fold upside with a push coming from barrel side. There are two superimposed front joints at the foreside and folding begins through a push on the lower member as causing a slight break up of toggle arms as forwarding the upper one to change the contact point from lower to upper joint giving the nearly same initial situation of toggle arms with a delay nearly sufficient for the bullet to go out of barrel. None of the axis of all joints are fixed and this also supplies some additional delay for ensured discharge.

        There is no superimposed front joints in Japan sample. Front and rear toggle arms begin upfolding through a contact line at upmost connection at the middle and this axis, through cleverly shaped counter contact faces, goes down as carrying the initial toggle arms situation through a break up pediod providing the necessary delay. Less moving parts, lesser machining and lower cost. It seems, even Mr Pedersen himself might not hope such a simplicity.

  5. I am surprised that the bolt does not hold open on an empty magazine. In practice it would appear that unless a Japanese soldier could manage to count his rounds, the first he would know that his mag was empty was when the rifle went click instead of bang. He then has to open the bolt, fiddle with the little catch to hold it open, strip two chargers into the mag, release the bolt and hope that in the meantime he hadn’t got a .303 or .30-06 between the eyes.

    I feel sure that if the rifle had ever gone into production, that feature would have to have been changed. However, looking at the beautiful machining which went into it, I can see why the rifle was too expensive for Japan to contemplate in a total war.

    • This is a prototype, remember? I don’t think it would have mattered, since the Type 96 LMG was probably a better investment and that was certainly much better than a BAR in terms of magazine capacity and ergonomic handling…

  6. This is a beautiful specimen and testimony to relentless Japanese search for self-loading rifle. In combination with rotary magazine in really stands out.

    One thing I noticed right at start is that Ian although this design had been tackled earlier, is tireless in re-introduction to the mechanism. Greatly appreciated!

  7. Even if the Japanese Army design team had realized the need for cartridge lubrication, it’s unlikely that they would have used a hard wax coating.

    Every other weapon they used that required lubricated cartridges (such as their LMGs) used either a built-in cartridge oiler or one built-in to the magazine loading machine. So the most likely “solution” here would have been the cartridges in their stripper clips being lubricated at the factory.

    The clips would probably have been packaged individually in packets of cellophane or a similar reasonably oilproof paper to reduce evaporation of the lubricant in storage and transit. I imagine they still would have been a bit messy for the infantry rifleman to deal with in his ammunition pouches. And of course there would always be the problem of the oil penetrating the primer pocket and deactivating the primer.

    The ironic thing is that a hard wax coating would not only have eased extraction, it would also have gone a long way toward reducing corrosion of cartridge cases in the notably hot and humid environments of the Southwest Pacific and Indian Ocean.

    One of my college profs (USMC, Guadalcanal, Class of ’42) had some very strong opinions on that subject re .30-06, .45 ACP, and .50 BMG ammunition. Most of them unprintable.



    • Eon:

      Good point. The Japanese were used to using oiled cartridges in their machine guns, and seemed to have no institutional problem with the concept, so it is a bit strange that they did not find a way to use them in this rifle.

  8. Does anyone know what Japanese small arm propellants were like in this era?

    Single or double base?

    Short grains or long strings?

    solid or perforated?

    The reason that I’m asking is partly to follow on from Eon’s comment about case corrosion.

    During WWi, the Tzarist regime contracted out some ammunition making to American plants. One of the requirements was for the neck and shoulder to be annealed, following necking.

    This practice was later adopted by just about everyone, and largely cured the problem of “season cracking” of case necks and shoulders – Season cracking because in India, brass cases cracked during the rainy season.

    One of the institutions that didn’t adopt case neck annealing, was British military manufacturers.
    Due to the length of the bundle of cordite strings used to load .303, the case was necked after the cordite had been inserted

    This precluded a neck and shoulder anneal, and left the necks stressed, brittle and subject to stress corrosion.

    The Japanese military took several cues from the British in terms of small arms development, including 7.7mm calibre and Metford segmental Rifling (which was well adapted to take an even layer of hard chrome electro plating)

    Was cordite another?

    • “Short grains or long strings”
      Data from Альбом конструкций патронов стрелкового оружия:
      6,5-mm cartridge with Spitzer bullet “88” (1905 year):
      Piroxylin powder, grain size (in mm): length – 1,75 width – 1,34 thickness – 0,29

      6,5-mm cartridge with AP bullet:
      Piroxylin powder, tube shaped

      7,7-mm cartridge with light bullet:
      Piroxylin powder

      7,7-mm cartridge with AP bullet:
      Piroxylin powder, tube shaped, size (in mm): length – 1,39 outer diameter – 0,70 inner diameter – 0,095

      7,7-mm cartridge with phosphorus bullet:
      same as above

      • Thanks,

        Tubes burn with constant surface area, whereas un perforated rods, flakes or grains burn with a reducing surface area (get slower as they burn)

        Cannon powders with 7 perforations actually burn with increasing surface area and get faster (then suddenly slower when they fall to bits), and ball powders with deterrent coatings mimic this to an extent.

        So it seems that the Japanese propellants were quite advanced in terms of burning rate control via their geometry.

        Is there any indication of whether they were straight single base nitrocellulose or double base with an addition of nitro glycerine?

  9. Very interesting site – I didn’t know it existed. I’m interested in buying spare parts for a Hopkin and Allen 22 cal., 7 shot revolver xxl

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