Many months ago, Rick Jamison published his results of experimenting with different seating depths for a 22-250. The powder choice and charge was kept constant. The closer the bullet was to the lands, the higher the velocity. Since pressure causes velocity, it is logical to assume the pressure increased as well with the lessening freebore.
My own loads bear this out. When the bullet is seated just off the lands (or in one case a tight throat), I'm getting published velocities with less powder than the published load. I'll get the obvious excess pressure indications before I reach the published powder charge.
Case capacity increases very little (percentage-wise), but freboare decreases a lot (again percentage-wise) when bullets are seated near the rifling for accuracy gains.
