Re: Kenton Turrets
I have a zeiss conquest 6.5-20x50 AO on my 340 Accumark and have Kenton Turrets. They are basically the Zeiss Factory Knobs custom engraved. I have a Speed dial one turn (18MOA) out to 900 yards. The markings are large and bright for my old dim eyes. I have taken elk out to 650 yards with them. Ziess scopes are pretty good about tracking 1/4 MOA per click.
You can try the box test and see how repeatable the return to zero is for your particular scope.
Zero your rifle dead center at 100 yards. Move up and right +5MOA then Shoot 3 rounds. Move straight down -10MOA shoot. Move left -10MOA shoot.
Move Up +10 MOA shoot. Move down and left -5MOA back to center. If your scope tracks well every group should be at the corners of a 5"x5" rectangle with its center on the bull.
If it doesn't track right, call Zeiss USA in Chester, VA and they'll fix it FOC.