H.L. covered it.
Take the BDC scope to the range, with your chosen load. Then shoot the ranges you want to shoot and you'll figure it out.
I used a BDC on a .30-06 for a short while and getting to 400 was easy. Once you shoot it and figure it out then write down, or just remember what yardage each circle corresponds with and you'll have a fairly reliable system
-Jake