If the velocity data you used for the dials doesnt match collected data from your handloads, you will be off your mark. If your dials were cut from "box" data from your factory ammo, you may have the same problem, however if its close enough it wont show that much until 500 yards or more.
Ill add, yes, I have had CDS dials and have tested 2 rifles that both had them out to 650 yards.