Leupold Rifleman, Rings, 1 Med, Fits Ruger M77, Matte Black 170351 Leupold ring mounts are a high-quality alternative to firearm manufacturer ring mounts or as a no-tap mounting method for most .22 rimfire rifles with an 11mm, 13mm, or 3/8'' dovetail rail. This model is designed to fit a Ruger M77, and because these rings are machined from solid steel, they offer superior integrity and tighter tolerances.