Not wanting to labour the above, some info from an article on the web:http://www.lazzeroni.com/ct_lrs.htm
To prepare yourself for long range shooting in the field you must begin with good equipment and that starts with the rifle. The long range hunting rifle must be able to put three shots into a 6 inch bullseye at 600 yards using 'premium hunting bullets' and put them there with enough energy left to effectively kill the animal with one shot.
The shooter must work with the rifle until he or she can consistently hit a 6 inch bullseye at 600 yards. One inch groups at 100 yards do not prove a thing.
Optics must be of the highest quality to withstand heavy recoil and have top power ranges between 12 and 24X. It is important to develop a technique that works for you.
I sight in my own personal rifles dead on at 300 yards using a Schmidt and Bender 4-16X50 or 3-12X50 scope with mil dot reticle. With the Lazzeroni muzzle velocities the fastest in the world in their respective calibers, this puts the path of the bullet no more than 2.8" above the point of aim out to 300 yards.
If the animal is at 400 yards, I center the animals chest between the horizontal crosshair and the first mil dot, while in the prone position using a good bipod. At 500 yards I place the first mil dot in the center of the kill zone. If the animal is farther than 500 yards or there is a significant crosswind, I don't shoot.