been extremely scarce, and Mr. Olson probably never had a good chance to examine a specimen and take it apart. I never thought I’d have a chance either, but suddenly their “extremely scarce” status was changed, via the military surplus arms market.
I first saw the 8mm Siamese rifles and actions advertised in the June 1, 1970, issue of “Shotgun News.” A member firm of the Interarms group once offered them as “M98 actions for rimmed cartridges,” and as “Sleek M98 actions designed exclusively for rimmed cartridges. Bolt face and magazine will accommodate such popular calibers as 45-70, 444 Marlin, 303 British and 7.62 Russian.” They were priced at $20 each or, in lots of ten, at $12 each.
Farther down in the ad complete rifles were described as “Cal. 8mmx52R M98 Thai rifles (Japanese manufacture) Model 45/46.” These rifles were priced at $15 each in lots of ten. Selling the actions and rifles in lots of ten makes me believe they had a considerable number for sale and might result in the rifle and action becoming well known.
I ordered one action and the invoice listed it as “RT M-98 Mauser Action.” I have been informed by a reliable source that the marking RT on this action stands for Royal Thai. Thus, the action and the rifle are given several different designations, such as: 8mm Siamese Mauser (the one I use), M98 Thai (Thailand), and Model 45/46. The southeast Asian country of Thailand was formerly known as Siam, hence the use of both names.
I have found but little history of the 8mm Siamese Mauser rifle, and not much of anything about the rifle itself.
Apparently most of these rifles were made in a Japanese arsenal—at least the actions, marked with three interlocking circles, are Japanese made. An item in the September 1955 issue of the American Rifleman mentions that some of these rifles were made in the Siamese government arsenal in Bangkok, Thailand, but I have no facts to prove this. Without much doubt, all of these actions and rifles that were for sale are of Japanese origin. I have no idea as to when or how many were made nor how long they were in service in Siam or Thailand, as the case may be. By the l960s the Thai army was fairly well equipped with the most modern arms, with the 8mm Siamese Mauser rifles being sold as obsolete surplus arms sometime before the 1960s. The rifle is somewhat similar to the old German M98 Mauser. The stock has a semi-pistol grip and a finger-grooved forend that extends to within about 5” of the muzzle. It has a half-length wooden handguard held in front by the middle barrel band with the front sling swivel attached thereto. The rear sling swivel is screwed to the bottom center of the buttstock. The front and rear sights are typically M98 Mauser, with the graduation markings in unusual Siamese numerals. If the rifle is complete, its most identifiable feature would be the sliding breech cover which is not connected to the bolt and must be moved manually. Another distinctive feature is the Japanese Arisaka-type tangs to strengthen the grip area of the stock. Siamese
Action Markings
The 8mm Siamese action I have shows several distinct markings. The Siamese crest, or coat of arms, is stamped on the top forward part of the receiver bridge. This crest is round and about
The Action
The 8mm Siamese is a copy of Paul Mauser’s M98 turnbolt action with certain modifications and additional features that make it one of the most distinctive and unusual forms of the basic M98. The modifications are essentially those needed to handle the 8x52R Siamese cartridge; the additions which are of Japanese influence include the detachable tangs and the sliding breech cover.
By carefully comparing the 8mm Siamese specifications with those of other M98 Mauser actions covered in this book, and by studying the photographs of this action and the others, it is easily seen that this is a peculiar variation of the Model 98 Mauser.
First, let’s see what this 8mm Siamese action has in common with the regular M98 military action made for the 8mm Mauser cartridge. The receiver is of the same general pattern and configuration, it is the large ring type and has the regular collar inside the ring, slotted only on the right for the extractor. It has the clip-charger guide slot in the bridge and the deep thumb cut in the left receiver wall. The receiver will accept a standard-length M98 bolt, though the receiver is only 8.50”, or .250” shorter than the standard M98. The receiver is flat on the bottom and has the integral recoil lug like all other M98 actions.
Siamese Mauser action open, tangs in place and breech cover slid forward.
Except for the bolt face and cartridge head recess, the bolt and firing mechanism are an exact copy of the M98 bolt. The straight bolt handle has a pear-shaped grasping ball. The bolt has dual-opposed forward locking lugs with the left (top) lug slotted for the ejector, a third rear safety lug, a guide rib, and twin gas-vent holes. The extractor is the same except that the hook is a bit narrower. The bolt sleeve, bolt sleeve lock, safety, firing pin, mainspring and firing pin head are enough like the standard M98 parts that they are almost, but not quite, interchangeable.
The bolt-stop and ejector are of the standard M98 pattern except that the ejector spring is riveted to the bolt-stop spring. The sear is also standard, but the trigger stem is cocked back a bit to bring the fingerpiece to a more rearward position.
In addition to these similarities, the Siamese action has the same functional features as the standard M98, including cock-on-opening, safety operation, extractor camming, etc. Also, everything is disassembled and reassembled in the same way.
The differences between the two actions are:
1. The breech cover. The Siamese action is fitted with a very neat spring-steel breech cover which slides to the rear to cover the loading and ejection port, and forward to expose the port. On each side of the receiver there is a narrow raised integral guide-rail over which the sides of the cover engage and slide. This is unlike the Japanese Arisaka receivers which are grooved for a sliding cover. On the right side of the Siamese Mauser breech cover there is riveted a hooked catch which engages notches in the side of the receiver ring and bridge to hold the cover either open or closed, and by which the cover can be slid back and forth. It is entirely independent of the bolt; it must be moved manually by grasping the hooked catch and pulling it outward. The cover can be removed by sliding it forward off of the receiver. The bolt can be operated and the rifle fired with the cover in any position, but it must be open to eject a fired case or to load the magazine.
2. Receiver shroud. The front end of the receiver has a shroud or collar extending about
3. Barrel shank threads. The receiver is threaded to receive a barrel shank about .990 ” in diameter with 14 V threads per inch. The regular M98 actions have a pitch of twelve threads per inch and usually for a thread diameter of 1.10”. The Siamese barrel is made with a shoulder large enough to abut and “set-up” against the front face of the receiver rather than having the breech face of the barrel butt against the inside receiver collar, as in the regular M98 action.
4. Left receiver wall. The 8mm Siamese receiver ring is slightly larger in diameter than
