An approximate rule for single-based powders is that pressure increases at about twice the rate of velocity. In this instance, loading the .30-06 to 65,000 PSI increase pressure over SAAMI maximum average by a little over 8%, resulting in about a 4% increase in velocity. With a "standard" 180-grain load at 2700 fps, this means velocity would increase about 108 fps.
Also, single-based powders usually increase velocity at the same rate as adding powder: If you increase the powder charge 4%, then muzzle velocity normally increases 4%.
With double-based powders, pressures and velocity tends to increase more rapidly.
