A 50mm objective lens on a Ruger M77 will require High or Extra High rings in order to provide clearance for the objective lens. So if you scope has a 1" maintube, these rings would be compatible.
Yes, these Ruger M77 Scope Ring Set 1 Inch High Stainless Steel rings should work just fine with a Vortex Crossfire II 3-9x50 scope.
I would recommend using a picatinny rail base that provides MOA as rings themselves will not offer different MOA options. We do carry 20 MOA options from Evolution Gun Works found using the following link:
https://www.opticsplanet.com/egw-ruger-10-22-picatinny-rail-scope-mount.html?_iv_gun-model=ruger-m77&_iv_cant=20-moa-1
Yes. This Ruger M77 Scope Ring Set will fit and function as intended, allowing for enough clearance for your objective lens.
This Ruger M77 Scope Ring Set will fit scopes with a 1" tube and will fit objective lens up to 50mm. I'd recommend the Burris Fullfield IV 4-16x50 mm Rifle Scope found using the following link:
https://www.opticsplanet.com/burris-200492-fullfield-iv-4-16x-50mm-obj-26-6-5-ft-100-yds-fov-1-tube-matte.html?_iv_parent-tube-diameter=1-in
This Ruger M77 Scope Ring Set will fit scopes with a 1" tube.
Yes, these will be compatible but you may be better off with the medium height version.
No, they should not.
No, you will need version of rings with a tube diameter of 30mm
Please email us at techsales@opticsplanet.com with your make model and caliber of your rifle and we may further assist you.