Type 46 Siamese Mauser

Siam, now known as Thailand, was one of the few independent south Asian nations around the turn of the 20th century. Looking to modernize its military to protect against colonial imposition, is decided in 1903 to adopt a copy of the Mauser Gewehr 98 rifle. Siam (which changed its name to Thailand in 1938) didn’t have the manufacturing base to produce the necessary quantity of rifles, so it contracted the job out to the Japanese arsenal at Tokyo (Koishikawa). Between 1903 and 1908, about 400,000 of these rifles were manufactured, chambered for an old-style 8x50R cartridge using a round-nosed projectile. This was called the Type 46 rifle, based on the Thai calendar.

About twenty years later the Siamese military was improving its machine gun armament, and revised its cartridge to a slightly longer 8x52R case using a modern spitzer bullet – as basically every nation did at some point in the early 20th century. The existing stock of Type 46 rifles were rechambered for this new cartridge, and it is fairly rare to find an unmodified example today. The conversion is easy to spot, as it also included grinding down the rear sight ramp to fit the flatter trajectory of the new cartridge. Range markings had been stamped on the side of the rear sight, and converted guns have these marks partially removed by the reshaping of the ramp.

As with all rifles made by the Japanese before WWII, the Siamese Mausers are of excellent quality, although many have led rough lives by the time they reach the hands of a collector today and are often in pretty rough condition. While they make an interesting addition to a surplus rifle collection, they have also long been used as the basis for conversion to .45-70 conversions, as the bolt and magazine are already designed for large rimmed cases, unlike most other military Mausers. This has led to them being rather more rare than one would otherwise expect.

I will point out (in a blatant commercial plug) that the rifle featured in this video is currently up for sale on GunBroker, should you be interested in having it yourself…


  1. Perviously altered or “sporterized” Siamese Mauser actions/rifles are also excellent candidates for conversion to 7.62x54r, a caliber much more common than 8x52r.

  2. I love the dust cover! Neat rifles. Truly “forgotten weapons.” Didn’t the Siamese/Thais also have an Arisaka in the same caliber as well?

  3. The history of Thailand being invaded by Japan is fascinating.
    The Thai’s actually won (that day) their first battle against the Nipponese but realized that would not happen on the next day.
    They signed a peace treaty (surrender????) with Japan and were “partnered” with Japan.
    Imperial Japan told them to declare war on the US.
    However, when the Thai ambassador (in DC) presented the articles of war they were told to go home and forget it.
    They did and most Thai’s worked under-cover to impede Japan and assist the Allies.
    I suspect some Thais were pressed into the Japanese Imperialistic Army (just like the Taiwanese, Koreans, and I suspect some Filipinos) and were were issued Arisakas. That’s just my guess.

    • Actually, you are probably correct. The problem with the gross complexities of war and wartime occupation is that so many otherwise unwilling participants ( on both sides, I might add ) are put in a position where they have little, if any, choice, either out of direct fear for their own lives and the lives of their families, or because to do otherwise would mean starvation and privation, or because the situation affords an opportunity for a better life, or a combination thereof. Ordinary folk usually have little or no choice in such matters where survival and well-being is of paramount importance.

      There are more benign variations on this theme, of course, as witness the increasing rate at which the occupation forces in Japan ( post-World War Two ) employed Japanese military personnel and civilians, who gradually began to realize that they would eventually be empowered as part of an inclusiveness that covered a long-term democratic process in which they would have a real say in their country’s future and, by extension, of themselves and their children. Obviously, the long-term political goal of the United States at the time was, like all similar objectives, orientated towards a regional stability and peace that would also be of ultimate benefit to the U.S. itself, particularly when the anticipated post-war divisions with the Soviet Union and its international goals came about, and when the desire to prevent a resurgence in Japanese nationalism and all it implied were also taken into account. Nevertheless, the accidents of historical timing were generally conducive to a win-win situation of sorts, and so it came to be that the democratic roots of modern Japan — with its strong ties as an unflinching U.S.ally in the Far East — were implanted.

  4. Interesting article. However, the video wouldn’t load past the intro point. After about 5 minutes, it loaded. I have one of these such ‘Mauser’, although I haven’t looked at it in a while. Let me hobble (bad knee)into the other room and look. Mine is one of the molified guns. The rifling is quite sharp, but rough, from age I guess. The gun is missing it’s buttplate, and I had to repair the two-piece buttstock when I got it. Unfortunately, the barrel is ringed, about 5 in from the muzzle. I saw a Siamese barrel on ebay, I may try and get it. Just for giggles, I slugged the bore. Bore size is .310. Not sure of the groove size. I put a .32 pistol slug through it first, which did not fill out the groove. A .324 cast boolit got stuck about 8 in down the bore, and I can’t find my heavy duty ramrod. Just had it 3 days ago, and know where I used it, but can’t find it. Interesting gun. If I can get that other barrel, I’ll get it installed, and shoot cast through it.

    • wondered what u ever did with the Siamese mauser? I know its an old post but would Luv to find some parts for one or trade u for some u need.

    • wondered what u ever did with the Siamese mauser? I know its an old post but would Luv to find some parts for one or trade u for some u need.

  5. An uncle of mine had one built in 30/40 Krag in the early ’70s. The reloads used were in the same range as a .308 Win.

  6. After all is said and done, how many of the Siamese Mausers are reckoned to still be in their original configuration and caliber? This might make a difference to hard-core collectors and enthusiasts.

    • I have a original, needs a floor plate, spring and follower.. Stock a little dinged, action very smooth lots of markings..

  7. Mr. Carlson you are correct. The Type-66 rifle was an Arisaka Type-38 chambered in 8x52mmR Siamese. It featured a Mauser-style tangent-leaf sight, an enlarged magazine for the rimmed cartridge and barrel bands held on with screws, but shared most of it’s features with the Type-38 including the Type 38’s reciprocating dust cover.

  8. I had one of the .45-70 conversions.The action was very smooth and supposedly more than strong enough for the .45-70 cartridge.

  9. Some of the reasons for reading on FW: it is informative, pictorially descriptive, in-depth and accurate. This article is no exception.

    What is also interesting from techno-historical prospective in the industrial power Japan had wielded already at beginning of 20.century – most amazing. As far as military planning of Siam kingdom, it also has to be acknowledged as visionary; thanks to this and other factors they managed to preserve their independence to these days.

  10. I guess when not even Bertram makes the brass anymore it does qualify as hard to get. Too bad, would be a neat addition.

  11. Just checked for 8x52mmR Siamese T66, in Donelly’s cartridge conversions manual:

    MAKE FROM: .45-70 Govt. Anneal case and run into F/L .40-65 WCF and .33 WCF dies (a form set will do the same job). Turn rim to .556″ dia. and back chamfer. F/L size in 8x52R die. Case may (usually) need I.D. neck reaming. F/L size again.

    Donelly gives the Bullet diameter as .323in.

    Interestingly, the case head dimansions are within a few thou of an inch (less than 6 thou – so just within military headspace tolerences) of the 8x53mm R Japanese Murata,although the shoulder and bullet dimensions are well out.

    Could we be looking at design input from the Japanese arsenal? or just copying of something which works?

    Donelly suggests making the Murata round from Mosin Nagant brass, by turning down the rim and back chamfering, expanding the neck, full length sizeing, cutting to length and fire forming,

    which could provide an alternative route to a siamese round too, depending on brass availability.

  12. Earl .. Once again I commend you sir.. You are a man of few words .. But the words you speak are well worth listening to. Your so correct in your assessment of why at times during wars people do not do as we think they could or should. Easy to say “they should have, or why didn’t they” from the comfort of our safe homes.

    • Thank you, Thomas, for the kind remarks. Just my two cents’ worth, really, expressed as best as I know how. Your perspective about the wisdom of 20-20 hindsight are right on the mark!

      What do you think of the Siamese Mauser? Have you had a chance to handle and fire an example? It is a very interesting piece of history, and of mechanical efficiency. It looks as if some of the other guys ( Mikey M., Ian H, Martin, et. al., have had a lot of experience with it.

      • You know Earl .. I spent all 1968 and half 69 as a member of a USSF Det assigned to USOM, Thi PARU. Had one chance to fire a Type 66 that was a Thi SF SGT’s “personal” (privately owned weapons in Thailand are a No-No) weapon he kept in the Arms room. Our range was 100, 200 and 300 yds. I remember it was accurate with ball, but not any better than the Type 99 Arisake and less so than a Mauser 98 or my Rem Model 1917 I had; but less recoil. Of course that was only one weapon. Definitely well made and better finish than a Type 99. But I have a LOT of respect for the Type 38 and 99. Never saw a Type 45.

        • Thanks for the informative reply — I think it adds a lot to our collective knowledge about this subject. Personally, I know something about these particular rifles, but nowhere near as much as you or some of the other contributors probably do, so I am still learning as we go along.

          • Earl .. thanks, however, and all others … I am by no means as knowledgeable as many of the folks who add so much to these discussions. There is a difference between having knowledge of weapons and “knowing” weapons.

  13. Got my hands on a Siamese mauser 45-70. Monte carlo stock. Magazine doesn’t like those rounds but golly what a hitter. Load it up. Small cannon.

  14. Got mine about 25 years ago. Tried lot of different powders,but it likes 4198Imr at 100 yds looks like 4 leaf clover, that’s with open sights.love mine would never part with it. Thanks for all the information.

  15. they are neat indeed, the Japanese and Thai Markings are very cool. There should be tons of markings under the stock from being built, and then re-chambered in japan. but I gotta say, finally I have an example in better condition then what Ian is showing me! Thanks

  16. I have had one of these converted to 30/40 we used a Sirplus 03A3 barrel l picked up for nine dollars in 1973 we had a gunsmith re-barreled the action I love it it’s been very Accurate and have only 70 Dollar total in the gun my load is 45 grans of 760 ball with BTSP 180gran Hornsby

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