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Arisaka safeties, like mauser, Springfield, Winchester 70 ect.,sometimes require fitting before they'll work smoothly. The Mukden knob could easily be made to work in the Koishikawa if need be....

All you pointed out really was a misleading post on another forum and a link to an ebay auction for a book the guy used as referrence.
What the guy at gun boards is saying is there 3 different knob...

Dont know where he got the info but arisakas dont have a half cock notch, and I'm reasonable sure that the striker has to be fully cocked before the bolt will even close. Nor can you hold the...

It may not be a drop in fit due to mfg tolerances but otherwise with a little fitting the three variations are interchangeable. At least that's been my experience.

ML, its been a couple years...

I'm with Aragorn, if it was in working order before you took it apart then either you aren't reassembling correctly or something was broken or otherwise damaged in the process.