standard National Match, NRA/CMP high power and service rifle has a stage at 200 yds, 300yds and 600yds. Everyone knows their come-ups (11 minutes up from 300 to 600 will always put you on target).
humidity, temp, light, air-density at altitude, how tired your eyes are all play a very minor effect that is worth a click or two from day to day.
WIND is important and its part of what you learn when you're shooting.
you will be shooting a 75, 77 or 80 from Sierra or Hornady and you'll end up with a different zero for each but close enough to be on paper (the paper is 6' square)
shoot good
Poole