My rifle and data from shooter match up perfectly, except around 500yds. Ive tested this many times and the results are always similar. At about 450 my bullet starts hitting high, peaks at about .75-1.25moa above data around 500-525yds, then is spot on from 600+. Ive gotten by with just using a dope chart built around average air density in my area, but id like to understand why this is happening. What am i missing guys?