If it were me, I'd sight in at 2.75" high at 100. According to the ballistics calculator I ran it through, assuming the .308", 180gr flat base PSP has a BC of 0.425, and the scope being 1.5" above the bore, that would give you a +/- 3" max point blank range of 265 yards. The zero would be at 225 yards and midrange trajectory would be +3" at 130 yards, -3" at 265 yards. POI at 300 would be -6.75", which would require hold over. Sighting in as such would give you the most range possible without requiring scope adjustments or holdover.

Mike