I have a BDC reticle in a 6-18 buckmaster. It doesn't necessarily have to be the highest power, just as long as it's the same power that you used when checking where the references hit at different distances...but not many people aren't going to want to be on the highest power when taking a long shot. Mine comes out pretty close to the first circle being for 200', then the next 300', etc. This is with a 25/06 shooting 120gr fusions at 2000' elevation, and around 30°F. The Spot-on program Nikon has can get you close, then the range to find out for sure where it hits.