Most scopes are junk. Unless you've thoroughly tested yours it's probably junk, too.
Admittedly, this is a mighty bold talk from a one-eyed fat man. But, none the less in my extensive experience, I have unfortunately found this to be true.
Someday, when I have the extra time (probably never) I am going to write a comprehensive article dealing with all of my perplexing scope "adventures." But for now, I think the following photos will give you some insight into the problems serious precision shooters face.
click photos to enlarge
So, did you look closely at the photos? Is this level of performance "good enough" for you?
This is why we at Quarter Minute Magnums only endorse scopes made by
Schmidt-Bender. The three models we use most are 10x42 PMII, 4-16x50 PMII and
5-25x56 PMII. All FFP only, all Mil-Mil only, all P3 or P4F and single turn when available.