http://riflemansjournal.########.ca/2009/10/reloading-seating-depth.html
"A good place to begin (and frankly to stay unless you're already at the Master level in NRA Highpower) is to jump 0.020" for conventional tangent ogive type bullets such as the Sierra MatchKing line or Berger's new designs and to jam 0.015" for VLD type bullets such as Berger VLD, Hornady AMAX, JLK VLD, and others of the secant ogive design.
There are slight variations in any lot of bullets, so when you check your finished rounds you will see some variance in the COAL - don't worry about it too much. The reason we selected the jump and jam figures given is because they allow for some slight variance and still maintain the basic concept of jump or jam. If you were to set the jump for 0.003" for instance, then a slight variance might have some bullets jumping, some right on the lands, and some actually jammed a few thousandths. By sticking to 0.020" jump or 0.015" jam, those same slight variances will have minimal effect - imperceptible for the Highpower shooter anyway."