You are correct. Ruger rings are typically sold in "mis-matched" pairs with the rear ring being one number higher than the front. For example my Gunsite Scout came with a #4 front ring and a #5 (taller) rear ring.SHOOTER said:I have a Ruger frontier m77 ... If I wanted rings for the rear mounts it looks like the front mount is higher then the rear mount. Are these special rings that are needed?