This Japanese manufactured complete bolt assembly with the first variation safety knob having the serrated radius and a large protruding hump is for the Type 38 Arisaka bolt action rifle in 6.5 caliber and is in good condition exhibiting a brownish gray patina with some rust and light wear. (file photo)

Note: Japanese Type 38 Arisaka bolt action rifles with the following arsenals and serial numbers have been observed with this part:

Koishikawa / Kokura: 00206