the bullet must cross the line of sight.... in order to be dead on at 100, 200, etc...
kind of like a football,
none the less I think it would be easier to just sight in at 100yds or 50 or 200 etc...
a scope adjustment of 1 click = 1/4 at 100yds... would be greater the closer to point blank...
buy a scope laser bore sight to get it close then sight it in at 50...100...200