Please consider donating to help offset our high running costs.
Photos of the front, side and another one of the back would be appreciated.
Use a sticky rubber ball to press on the back and unscrew. Still looks like a screwback with markings worn/polished off.
Crown is a replacement, and apart from some case pitting it looks good, especially with the black dial.
Don’t these backs usually have some hexagonal raised portions to grab with a case back opener?
That case back would have to be ground significantly to look like that and screwing it on in that state would mean that it would either remain losely fitted or there would be marks on case back or sider due to tools used to tighten. Regardkess, althiugh the watch looks good, the case back let's it down ... take it to you watch maker and get him to remove it. You would be better off keeping an eye out for a replacement on the bay.
Why did you start a new thread about exactly the same thing?
https://omegaforums.net/threads/odd-polerouter-caseback.115294/