, the best way to calibrate the Elevation Knob is to do it the way they taught us on the ANG Team, buy a cheap six color Testor's model airplane paint kit. With your 200 yard zero, take a toothpick and dab it in white paint and put it at 12 O'Clock on the Receiver at the knob and mark right across on the knob with Yellow, Add clicks to 300 and put a dab of green on the knob, crank up to 600 and put a dab of Red on the knob. Whatever range you need, now all you have to do is align the correct color on the knob with the white dab. It's faster than any other method.
The big thing to remember is that, like any other firearm, this will work for whatever load you use to sight-in. If you change loads, say, going from HXP to a Matchload with a 168 or 175 you will have to tweek the clicks by one or two.