I have used the CDS before and they are very accurate I have only used to 500Y , the more information you can give the custom shop the better, CHRONO your bullet speed give them an average , I use 5 shots , if you want your dial super accurate then do like other Custom dial makers ask you to do shoot your gun out to as far as you can ,and record the clicks to each yardage, remember the more accurate info ther better. Leuo CDS are only one revolution dials you may want to get your sight in at 200 to get you more yards dowm range, the first dial I had cut was a zero of 100y and max was 675 yards 270wsm 110gr bullet, so i would use a 2-3 yard zero . Hope this helps