My only experience with the Flues models has been with the later ones, with the screw. I shot a 20ga for several years & it was fed a steady diet of 2-1-7, both factory & equivalent reloads.
The big change in the "NEW" progressive powders was not so much to reduce pressures but to allow heavier shot loads, higher velocities or both without increasing pressures. These powders were used in the heaver loads with normal loads staying the same as had been previously used.
The heavier loads (More Recoil)) was what cracked Flues frames, not higher pressures per se.
