Originally Posted By: Drew Hause
To convert PSI as determined by LUP (converting a measured mechanical change to an estimated pressure) to PSI as measured by modern piezo transducers, add 10-14%

To convert TONS as determined by LUP to modern transducer PSI use Burrard's formula.

UNLESS, like Coxe, you used a Tarage Table for PSI and to get TONS simply divided by 2240, or vv. frown THEN add 10-14%

Which is what these numbers are; published some time after 1920



and these in 1927



Ballistite 4.9 Tons X 2240 = 10,976 psi + 10 - 14%



Darned Brits. There they go again! The first table refers to "velocities over 120 feet" (40 yards)--which is why those velocity numbers are so low. I knew that they were using something called "observed velocity" (average velocity over 20 yards)--which shows up as recently as 2005 in my "Eley Shooter's Diary". But they also sometimes use true muzzle velocity (at the muzzle as opposed to our 3 foot velocity figure . . . typically about a 100 fps difference.) But I've also found reference--in a BASC Information Sheet on "CIP Regulations on Steel Shot Ammunition And Shotgun Proof" to: "Mean velocity, measured at a point 2.5 meters from the muzzle . . . " So now, in addition to those 3 different "modern" methods of measuring velocity, we now have to remember that if we see something really old from the Brits on velocity, it's the average over 40 yards . . . which clearly means that those loads aren't nearly as slow as we might think.