Have one question. What is a good starting point for seating depth for 140 grain bullets in the 270 WSM in reference to distance of the lands?
Kiss the lands.....
Back that off a C.H.....
Seat to mag box confines....
If using Barnes TSX's use the maufacturer recommended standard of .050 off the lands....to start.
Too many variables to reccomend an exact seating depth but if it were me I'd look for a sweet spot, with standard cup and core bullets, somewhere in the .005 to .020 range off the lands....providing they feed through the magbox.
You really can't go wrong as long as you maintain a level of consistancy and don't make large adjustments too quickly from where you decide to start....baby steps.
I would avoid craming the bullet into the rifling though.......