RGH;
The conversion of British long tons to lbs is simply Tons x 2240lbs. This of course gives you the 6720lbs for 3 tons. The fly in the ointment here is the 3 tons is in reality "Crusher Pressure" which is not absolute pressure per square inch. Pressure as taken with a pizoelectric crystal is assumed to be exact. For "British" tons a formula has been given which is (crusher tons x 1½) - ½ = PE tons, thus (3 x 1½) 4½ - ½ = 4. Then 4 x 2240 = 8960 psi. This formula was derived from a pressure bbl having crushers mounted on one side & PE gages on the other at exact same distance (1.000") from breech & recording simultaneous readings from the same shot. It was said to have been adequately correct for pressures within normal shotshell ranges. The problem thus is not one of converting tons to lbs, but one of converting crusher pressure to psi.
