Читать книгу Bolt Action Rifles - Wayne Zwoll - Страница 42
ОглавлениеMauser— Siamese Mauser FdH
The right side view of the Japanese-made 8mm Siamese Mauser action minus the tangs and sliding breech cover.
IN HIS EXCELLENT book Mauser Bolt Rifles, Ludwig E. Olson describes so many different models, variations and styles of Mauser turnbolt rifles that scanning the index never ceases to amaze and baffle me. Many of these are described in some detail, but the one listed as “8-mm Mauser, Siam,” (on page 126 in my copy of this book) has but one short paragraph, another short note about the 8mm rimmed cartridge it fired, and that’s all. This is understandable for these rifles have 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 ” in diameter. A line of five Siamese numerals or letters is stamped on the receiver bridge below the crest, and another line stamped across the bridge. Although I have been unable to get these lines deciphered or translated, they probably refer to the date of manufacture and model designation. The Japanese arsenal proof mark, three interlocking circles, is stamped on the left receiver wall. Arabic numbers are stamped on various parts of the action, but those which are apparently the serial numbers are stamped on the flat bottom of the receiver ring and on the left side of the front tang of the trigger guard.
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 ” forward as on the Polish Radom M98 Mauser. The purpose of this collar is to hold the rear of the handguard in place.
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 the large ring M98 action, but unlike the latter, there is no “step” between the left side wall and the receiver ring. This means that the left receiver wall is much thicker in the Siamese receiver, and the reason that it is so made is because of the breech cover guide rails. The average M98 Mauser left side wall is about .155” thick, while the Siamese Mauser is about .200” thick.
5. Bolt face. The recessed bolt head will accept a cartridge rim no larger than about .564”. There are no lips extending forward on the left side of the rim recess as in the regular M98 Mauser action. The rim recess is cut away at the bottom to allow the cartridge rim to slip under the extractor hook on feeding a cartridge from the chamber, which prevents double loading.
6. Extractor hook. It is narrower than the extractor, being only about .300” wide.
7. Tangs. Separate upper and lower tang extensions on the 8mm Siamese action extend rearward about 3” and are inletted into the top and bottom of the grip of the stock. They are milled at the front end to fit closely against the rounded end of the integral receiver tang and trigger guard, and are held in place by the rear guard screw. The tangs, connected at the rear by a screw, are almost exactly the same as those used on the Type 38 Japanese Arisaka 6.5mm rifles and carbines. They are used to strengthen the grip area of the stock.
8. Magazine. The combined trigger guard/magazine is of one-piece milled steel construction like the regular M98 Mauser. The front and rear ends of the magazine box, however, are slanted forward at a sharp angle. This slanted magazine box permits easy loading of the larger rimmed 8mm Siamese cartridge, the slope preventing their rims from catching on each other. Each cartridge pushed into the magazine moves to the rear so that the next cartridge inserted over it will have its rim ahead of the cartridge rim below. To gain adequate magazine capacity, the rear of the magazine box was made about ¼” deeper than the regular M98 8mm Mauser. The floorplate of the Siamese action is not hinged, but is quickly detachable via a latch built into the forward part of the trigger guard bow. Due to the slanted magazine box, the trigger guard bow is positioned back farther than the regular M98 and for this reason the trigger shank is bent back as mentioned earlier.
Bolt head of the Siamese action, showing: (A) twin gas-vent holes; (B) extractor; (C) right (bottom) locking lug; (D) undercut cartridge head recess; (E) ejector slot, and (F) slotted left (top) locking lug. The bolt also has the regular M98 Mauser short guide rib and the rear safety locking lug (not shown).
Incidentally, the front and rear guard screws of the Siamese action have the same thread pitch as the regular M98 Mauser guard screws, but the Siamese screws are slightly larger in diameter. However, regular M98 Mauser guard screws can be used in the Siamese action, but not conversely.
The 8mm Siamese Cartridge
Generally referred to as the 8x52Rmm Siamese, this is a rimmed, bottlenecked cartridge normally loaded with a 181-grain pointed, jacketed bullet. Not much is known about it—when it was adopted or who developed it. It’s probably merely a ballistically improved version of the older 8x50R Siamese Type 45 cartridge; a little longer case, a pointed bullet and more powder.
Fred A. Datig in his book Cartridges For Collectors designated this cartridge as the 8x52R Siamese Type 66—so does George C. Nonte in his book Home Guide To Cartridge Conversions. I don’t know what the “Type 66” means. Regardless, if you have the Siamese Mauser rifle and want to shoot it, there is very little chance that you will ever find any factory-loaded ammunition for it. If you are a handloader, Nonte suggests the following: make cases from new 45-70 brass, trim to 2.04” and turn the rim to .560” diameter. Full-length resize in a 33 WFC die, size down the neck and push the shoulder back in an 8mm die until the case will chamber, then fire-form. Use .323” bullets.
Comments
The 8mm Siamese Mauser action I received was in very good condition. Very well made and finished, it was as smooth in operation as any military M98 Mauser I’ve ever handled. I have no way of knowing the kind of steel used in making the receiver and bolt, nor do I know what heat treatment was given these parts. If I might guess, I’d say that if the arsenal in Japan that made the Siamese Mauser actions also made Arisaka actions, the same steel and heat treatment were used for both. I know that a file test for hardness is none too reliable, but it can be used to compare the hardness of such parts as rifle bolt heads. To do some comparing I took a file to the locking lugs of a couple of M98 German Mauser bolts, but could not get a good bite. This is normal, for most M98 bolts are very hard. Then I tried the file on the Siamese bolt and I could cut both locking lugs and the front edge of the bolt. Next, I got out two each of the Japanese Type 38 and 99 Arisaka bolts and, with the same filing effort, cut all four of them. Because the M98 Mauser bolt has smaller locking lugs than the Arisaka it is probably a good idea that they are made very hard. I don’t think they have to be made as hard as they are for strength alone so I see no reason why the softer bolt in the Siamese action wouldn’t be just as strong. However, to be on the safe side, the Siamese Mauser action should be limited to cartridges that do not develop much over 45,000 psi breech pressure.
The 8mm Siamese cartridge (8x52R) has a rim diameter of .561” and is about 2.925 ” overall. You’ll recall that the ad I read called this action suitable for the 45-70, 444 Marlin, et al. I checked a number of cartridges in this action, and here’s what I found.
45-70. The 45-70 rim is .608” in diameter, too big for the .565” diameter recess in the bolt face. The front of the magazine well (cartridge guide lips) is also slightly too narrow to pass the 45-70 rim. The unaltered magazine will accept and hold 45-70 cartridges, but the bottom or last cartridge is not tipped high enough in front for it to feed correctly. To use 45-70 cartridges, the bolt face recess must be opened up to about .610” and the front of the magazine well widened—not difficult to do. The latter job will most likely end the feed problem of the last cartridge. With these modifications this is a good action for the 45-70 cartridge. Or do as the late George Nonte suggested; turn the rims down to .560 diameter.
444 Marlin I don’t think the use of this action is going to be too successful with the 444 Marlin cartridge. The 444 rim diameter is only about .514”, and the 8mm Siamese bolt face recess is too large for the too short extractor to hold this cartridge in place for proper ejection. Also, the magazine will not retain the first cartridge inserted into it; similarly, if the magazine is loaded with more than one cartridge, the last cartridge will pop out after the other cartridges have been fed. This last problem can be corrected by rebuilding the follower, but I know of no practicable way to reduce the bolt face recess. Therefore, if you want to use this action for the 444 Marlin I’d suggest you solve the bolt face recess and magazine problem before going to the trouble and expense of fitting a 444 barrel to the action.
303 British The 303 British cartridge is normally loaded to an overall length of 3.075” and it will just enter the 8mm Siamese magazine, with little length-room to spare. It has a rim diameter of .540”, and it fits the bolt face recess OK, although for better ejection of the fired cases the extractor hook should be a trifle longer. As with the 444 Marlin cartridge, the 303 British case rim is a bit too small for the rear width of the magazine well, and in order for the magazine to retain the first cartridge inserted into the magazine, or the last cartridge after the others have been fed, the right side of the follower ridge (left side of the follower) should be built up slightly. This can be done by sweating (soft soldering) a thin piece of sheet steel onto it. The 303 British cartridge does not fit this action perfectly, but it comes very close, and with the modifications to the extractor hook and follower, the Siamese Mauser action should prove to be ideal for this cartridge.
Left side of the Siamese action with the breech cover, but minus the tangs.
Top view of the Siamese action with breech cover closed. Breech cover is independent of the bolt and must be moved manually by grasping the small hook at the right rear of the cover, pulling it out slightly then moving the cover. The spring snap hook locks the cover in either position. The cover can be completely removed by sliding it forward off of the receiver. Below—Action with breech cover open.
7.62mm Russian This is the old Russian military cartridge with rimmed case, and is not to be confused with the more modern 7.62x39mm Russian or the 7.62mm NATO cartridges. The 7.62mm Russian case has a rim of .564” and is loaded to an overall length of just over 3.00”.just short enough to fit in the magazine of the 8mm Siamese action. The several samples of this cartridge which I have in my collection fit perfectly. Norma has loaded this cartridge for several years and it is a good round for big game hunting. If you want to build a 30 caliber rifle on this action, then the 7.62mm Russian is a good cartridge to choose.
Other Cartridges
I found that the 30-40 Krag and the 348 Winchester cartridges are both quite suitable for the Siamese Mauser action. In fact, the 30-40 cartridge with a rim diameter of .545” fits this better than the 303 British. My opinion is that the 30-40 cartridge would be a much better choice than either the 303 British or 7.62mm Russian. Many wildcats have been developed on the 30-40 case—the 6mm Krag, 25 Krag, 35 Krag and the 30-40 Krag Improved. If not loaded to the extreme, any of them would be OK in this action.
The 348 Winchester is also well suited to this action. Its rim diameter of .610” requires the bolt face recess to be enlarged, but other than that, the 348 functions perfectly in this action. There are also some very fine wildcats based on this case—30/348 Improved, 35/348 Improved, 40/348 Improved, 44/348 and 450 Alaskan.
Gunsmithing
Because it is a basic M98 Mauser action, most gunsmithing work that has to be done, or can be done, on a regular M98 for sporting rifle use can also be done on this oddball Siamese Mauser. For example, the bolt handle can be altered as usual by heating the shank and bending it down, or forging it in bolt handle bending blocks, or by cutting off the handle and welding it or a new bolt handle into the new position. Low scope safeties made for the M98 Mauser can also be fitted to this action. Several commercial M98 adjustable single stage trigger mechanisms will also fit, though on some it would be a good idea to heat and bend the finger-piece of the trigger back so it will position better in the trigger guard bow.
The breech cover can be removed and discarded, its guide rails ground off level with the receiver, and almost any top scope mounts made for the M98 Mauser can be fitted to the receiver. A receiver sight for the M98 Mauser will also fit this action. The breech cover can be retained and used with a receiver sight, but if this is done, the hook on the breech cover catch should be made longer. The breech cover cannot be used if top receiver scope mounts are used.
Stocking the 8mm Siamese action rifle is going to be the biggest problem for the amateur gunsmith, but if he can make a stock from a blank for any other centerfire turnbolt rifle, he’ll be able to manage this one. In stocking the rifle the separate tangs can be discarded.
This chapter may look a little bare; not having all of the usual detailed pictures, parts lists and other specifications. However, except for the hinged magazine floorplate and floorplate latch, the component parts of the 8mm Siamese Mauser are essentially the same as the M98 Mauser military action— covered elsewhere in this book.
