just cut into the neck of a resized 270 win case, place a 150 grain bullet in then closed the bolt on it softly, pulled the bullet out, changing the bullet every 3 measurements.
After 15 measurements I took the average as my distance to lands.
I repeated the exercise with a 130 grain Hornady Interlock and got that distance.
I have also taken the max and minimum loading data from 3 manuals for the bullet weight and powder to be used and averaged the data given for my min and max loads.
I want to make up a batch of ammo, loading 5 rounds each at 0.5 grain increments to see which one gives the best grouping.
After I have that data I want to work out how far from the lands I need to seat the bullet for best accuracy.
As regards my starting distance from the lands, would you advise 0.030" or the often mentioned 0.015"?