Measured my rings and used Brownells’ descriptions to figure out I have a low setup. From there used the Ruger reference chart to determine I needed a 5B and picked one up from Optics Planet. Thanks for the help!
Food Court Apprentice
Semper Paratus certified AR15 armorer
Well, I saw this a little too late. But... if the Bicentennial M77 uses the same style ring mounts as the M77 MK2, and if your other solution does not pan out, then I could send you these Ruger to Weaver bases that open up a ton of ring options. Let me know if you would like to try them.