Siamese military contract Type 66 Arisaka rifle.
The rifle was manufactured in Japan in 1920-s for the Siamese army. The design is based on Arisaka Type 38.
Type 66 rifles were never exported to the United States, and are very difficult to find on the collector market.
Similar guns are described in "Military Rifles of Japan 1897- 1945" by Fred Honeycutt, Jr. and Patt Anthony, pages 188-198 (first edition).
Siamese "Charkra"  is stamped on the receiver (please, see pictures)."Charkra" was an emblem of the royal house of Siam.
It represented the throwing weapon of ancient Khmer gods and consisted of twelve flaming blades.
Some Siamese characters are stamped on the receiver (the model description in Thai numerals).
The rear sights are also calibrated in Thai numerals. The Thai serial number is stamped on the receiver.
The Arabic serial number is stamped on the bolt. I am not sure if the rifle displays serial, or assembly numbers on its parts.
Two piece stock with a handguard.
The following parts are missing from the rifle: the cleaning rod, the receiver dust cover, the magazine floor plate, spring and follower.