DAN,
I might also add that you might want to learn and setup your chart in Minutes of Angle instead of clicks. Most programs will readout both. If you needed a hold over at 600 yards of 73.5 inches or 49 clicks you would have to count 49 clicks, nearly a full turn on your scope. If you set your chart up in MOA you would need 12.25 MOA. Simply turn the elevation turret to 12 + 1 click. The MOA system is much faster and less likely to make a mistake on. No matter what you use you will need to shoot at the range you intend to use the system at to confirm your chart prior to use in the field. You may find problems like Bounty Hunter spoke about where the click values are not exactly 1/4 MOA. I had a Leupold LRT 6.5-20x that had .25 windage but the elevation was .34 MOA. I discovered this when confirming my drop chart. By the way Leupold quickly fixed the problem for me.
Shawn