I have an electronic copy of an Article from Guns magazine, March 2000, by Holt Bodinson.
It lists test data from the 1960s:

82gr / 3dr FFF, 1 1/8oz 7.5, 1205fps, 4900psi
109grs/4dr FFF, 1 1/8oz 7.5, 6900psi (no velocity offered).

That's why I find pressures reaching as high as 10,000psi, even with FFF, so surprising.
RG