I talked to a guy who was shooting a bolt action .22 rifle at 400 yds. He was sighting 10' above the target.
These guys aren't playing with little pansie azz calibers. These are REAL guns specially built for distance shooting with very large calibers.
Another thing to remember, less than 50% is the gun. That or more is the shooter. The calculations involved for the shot are almost NASA deep. I read a quote by an Army sniper that said " a sniper is a mathematician that can pull a trigger".