Lyman has published a Black Powder Handbook in the past, may have a current edition in print, not sure. Pressures were given for shotgun loads, though primarily for muzzle loading. As black is much less sensitive to external conditions than smokeless I suspect pressures would be similar loaded into a regular hull. It is noted that pressure recorded by DuPont back in the late twenties I believe it was with then current Dupont FFFG black using 3 drams under 1¼oz shot showed a pressure of near 9,000 psi, higher than what Lyman recorded in their testing using "Modern" GOEX powder.
