I have used the Boone and Crokett Reticle scopes, as well as other Reticle systems. The system that has worked best for me regarless of which range I chose to zero my set up was to use actual drop data measured at exactly 500 yards. First, I'll zero my rifle for either 200 or 300 yards, depending on the velocity/ballistics of the cartridge. I will then draw a target circle at the top of a 5' high paper and shoot a group, aiming at the top dot using my Reticle zero being careful to note all conditions, and making are there is no cant. The actual group will be at the actual drop down in the lower portion of the paper. If all looks right, will then sight through the scope, placing my Reticle zero on the top dot and turn the power ring on the scope so the 500 yard Reticle mark is in the center of the lower group. I'll then shoot at 500 yards, using the 500 yard line on the Reticle to shoot and check to make sure I am on. If so, I'll mark the spot on the power ring, and also confirm the impact points for the windage hashmarks, and hashmarks for the intermediate yardages on the Reticle so I understand the exact POI for these Reticle holds. Finally, I'll test to make sure that my power setting mark is repeatable to the mark to make sure that it returns me to the same impact point. Sounds like a lot of work but it is precise, and has worked very well for me. IMHO.