I bought these to replace the rings that came with my Ruger M77. They are a drop in replacement but involve little bit more work to install because of the windage adjustment. However, that allowed me to center the scope's adjustment and then roughly bore sight the scope for windage, insuring a better alignment with the bore. These are, in my opinion, better than the Ruger rings.
Pros: Windage adjustment on the rings
Cons: More difficult to set up than stock Ruger rings
This review was written in the old system and had content requirements that are different than reviews written today.