SAAMI specifications are in CUP and PSI, so it doesn't make any difference when the manual was written, if it includes pressure data. SAAMI has been around since the 1920s, long before there were any transducers being used. However, transducers were used in the early 1960s by DuPont and some others as recorded in "Absolute Chamber Pressures in Center Fire Rifles", L.E. Brownell and others, July 1965, University of Michigan.