It is unlikely that a pedestrian grade hunter (such as myself) can reliably make a first shot lethal hit on a deer size target very far out beyond 250 yards-which is the average maximum point blank range of a properly sighted high power rifle. The number is smaller for some weapons and larger for others of course. Inside that range, the difference for windage, bullet drop, muzzle velocity, bullet design, etc. is small enough that the real issue is proper sighting, and the technique of the shooter. If a person can't put 5 shots reliably on the same horizontal line within a few inches left to right at 250 yards, then they would be better served to calculate the windage of peeing in the wind than to confuse themselves with calculating windage. Which, as BoHuntr said, is tough to do with an animal milling about at 400 yds. This would include me.
WI angler knows his stuff when it comes to the long range stuff. He also spends a LOT of time sending bullets 1000 yds down range.