bore sight it
one of the ranges do it for free or next to nothing
what i do is take shots at 25y see where it goes, get a25 y zero
then i calculate how high the scope is, drop it down that much 6-8 moa - 2-3" for bullet drop (usually most rifle ammo will drop that far at 100y) and that will get me more or less on target at 100y and i re-zero for 100y
i would be careful where you try this method though as in many places you mgiht want to be careful of where your bullets are goin
I did this about 2 months ago to align my vertical crosshair. I took some fishing line (pretty heavy pound test for larger diameter) and used a sharpie pen to color it black. Using the colored line i hung a small weight (ziplock bag of empty brass shhhhhh dont tell anyone) from a nail on a white wall. The weight garantees the line will be vertical. Set the scope to the lowest setting and look at the line. When you get the vertical hair on the line your good to go. Tighten your rings down, check it again. If no change, bore sight and head for the range. Hope this helps.
Really any kind of line would work. it just has to be thick enough to show up in the scope. I tried using the corner of a wall but I couldnt get one far enough away.
I have way too much time on my hands for figure this stuff out. LOL I am going to be doing this tomorrow evening when my new rings and rail get here.