The siamese mauser (thai army) bolt action differs from the 1898 mauser in the following details:
1. The action was designed for a large rimmed bottlenecked cartridge (8mm Siamese) with appropriate changes to the bolt face, extractor, and magazine box (floorplate protrudes below stock line) to fit the cartridge. The rear of the magazine box is taperd, for stacking of cartridge rims. The mauser 98 was designed for rimless cartridges, and lacks these features.
2. A sliding Arisaka-style dust cover slides over the bolt cutout and is exposed by working the bolt.
3. Barrel shank threads are different from the standard large-ring mauser '98.
4. This is (was) a favored action for rebarreling to a large caliber sporter in .45-70, .444 Marlin, .45x2 American, etc calibers and loading hot since the bolt action is much stronger than most single shot contemporary rifles.
These thai rifles were built in Japanese arsenals for the Royal Thai Army, same as the type 38 Japanese Arisaka service rifles. The carry the intertwined circle manufacturer's mark (representing a stack of four cannon balls).
AFAIK, none of the parts will directly interchange with those from a mauser '98 action.
HTH
John
