The Stoney Point bullet seating comparator and a chaep digital caliper is all you need with a 270 modded case. The instructions are clear and easy to follow and you are using the bullets you are going to shoot.
I use 60grs with CCI 200 primer RP or Norma cases an seat the Hornady 130gr spire point bullet .025" off the rifling. this gives .5" -.75" groups in my rifle depending on how good I am on the day.
The H spire points are very good and cheaper to practice with too. I have killed plenty of deer with these and all have been one shot kills.