It's been a while since I read about CS1s but my memory is that the majority of revolvers that were stamped CS1 were actually made for the US civilian market. After becoming famous by government purchases they sold well to civilians. Consequently overseas sales to civilians are no surprise.

I mostly posted to refer you to this thread that is stored in the notable threads thread. US Customs Service 686 CS-1

One of the numbers on the side of the grip frame will be something that all S&W handejectors have, an assembly number. It will also be on the yoke and the back side of the side plate. Assembly numbers are stamped before serial numbers are assigned. They are there to make sure the yoke and side plate stay with the frame they were fitted to. Assembly numbers are not recorded and there is no effort made to prevent them being reused so after final assembly they are of no further interest.