I've used Millett bases and Angle-Loc rings for 25 years, on both centerfire rifles and ML's. Never a problem with mounting or alignment and adjustment. I deviated once, with the last ML I purchased, a CVA Kodiak. CVA recommended some in my owners manual (forgot the brand) and I tried them. My Zeiss scope was at the end of adjustment when I got it zero'd. Then my shot groups were all over the target. Changed to the Angle-Loc, sighted in with only a few shots. Spot on. There are other good brands out there, I just haven't tried them. Too much success with Millett.