A friend directed me to a post on the BOCN that included quite a few gauge maker symbols I had not seen, The image below was submitted by a Czech member of the BOCN. It includes the GR logo.
The list of gauges in the original post were all 9mm Chamber Gauges, but I welcomed other gauges and makers anyone wanted to post.
This BOCN post included the following image:
This list includes a lot of maklers not resented above. If I cut and pasted these additional logos, would you be willing to help with the identification???
Please let me know.