Agree on the seating by 'feel of pressure' method. As we know, the amount of pressure is usually part of the fun of working up the load for a particular rifle and bullet type. Once the amount of seating pressure is found that the rifle with that load prefers, applying that same pressure from load to load is the key to repetitive accurate shots.
I.E. When I'm shooting PRB in my sidelocks, they usually prefer more seating pressure then if shooting the inlines with either Powerbelts or sabot'd type bullets.
Seems as though when shooting the inlines with the Powerbelts or sabots, they only require to run the load down till it stops for best accuracy. To much seating pressure results in fliers.
Those that are better informed, correct me if I'm wrong, but doesn't this have to do with not applying to much seating pressure as to deform the 'cup' on the sabot type rounds?