[Unclenick]

The trick with pressure is you have to remember velocity and bullet mass will give you muzzle energy which gives you the average force behind the bullet in the bore. After dividing that force by the bullet cross-sectional area, you get average pressure. But because the peak pressure and the muzzle pressure aren't changed the same amount when a powder charge is changed, either by weight or by type of powder producing the velocity, you can't get to peak pressure directly from velocity. That takes using a program like QuickLOAD to mimic a test gun load, then altering it to mimic what you are getting for velocity, and then seeing what the resulting percent change in peak pressure was and applying that percent change to the measured test barrel pressure. What you can say, though, is that if you get less velocity from a load than the published load got, even after adjusting for barrel length, then you are running at lower pressure than the same charge got in the test gun.