The pressure figures at various distances from the breech shown above are significantly different from those shown in the Dupont chart that dates from 1933. All 4 powders (3 types of Dupont smokeless plus FFFg black) produced pressures reading between 3500-4000 at 10 inches. That's measuring in LUP, so converted to psi, the readings would all be over 4000. Sherman Bell's tests, reported in Doublegun Journal, gave readings ranging from about 1500 to just under 2000 psi at 12 inches. Per those figures, while pressure does indeed drop rapidly, it doesn't drop nearly as rapidly as the figures posted above would indicate.
