About 800 yds max
About 750yds for accuracy being as you do not want to be at the total top of the dial.
If you have a one piece base on your gun, it is easy (relatively speaking) to shim the rear of the base with cutout peices of soda cans. Run a search on "shim" with username ABINOK, if it interests you.
There are a number of ballistic calculators available up on the bullets ballistics and barrels section. You should pick one or more and learn how to make your own calculations. It is fun and easy and allows you to test bullets in your computer on the days it is too miserable to be outside shooting. I don't mind doing it for you but it is a part of long range hunting just like pulling the trigger.
If you want to shim and have a two peice base it is more difficult and you probably want to post a separate question.