Thank you for all the information/advice, greatly appreciate it. I decided to go with the Forester Field (for now) which as I understand turns may result in a fail although the rifle may still pass under British milspec. I found the gauge for $20 so not much of an investment. If it fails, I will probably go with a BDL Ltd solution as I have also dealt with Brian Dick and was very impressed with his products/services.
Thanks again and happy holidays to all
Best
Robert