Hi Vern,
I, for one, will look forward to seeing your detailed photos.
I am glad to hear your name is behind the "hold" note next to the gun on the Simpson web site.
It is difficult to understand what Walters may meant when he wrote that info. Maybe it is as simple as the one and only gun he saw in person had some field-work done (i.e. removal of the Gesichert and a replacement, unmarked extractor...???...or maybe that one had a frame with a polished thumb safety and it was over-blued...???).
With your detailed photos, we can see a Siamese in more detail and learn a bit more from it.
Wonder what type of holster the police in Thailand used...??? That would be the 2nd. half of a challenging search...
Since many of the Dutch holsters from Indonesia have survived, you should be hopeful in your Thai search !
My search woud start in all the Thai restaurants near my home run by an older couple who immigrated. You might get useful info and a great meal, at a minimum...
