Thank you for sharing Jim, and I added the numbers here
https://docs.google.com/document/d/1...U/edit?tab=t.0
In a 1927 Western Cartridge Co. flyer “Super-X The Long Range Load” by Capt. Chas. Askins, the Super-X 10g 1 5/8 oz. “about 4 1/2 Drams” (DuPont Oval) No. 2 shot Full choke 32” barrel, average velocity over 40 yds. 1030 fps; “up to 13,000 psi” by crushers = about 14,500 psi by modern transducers.
Some time ago Armbrust ballistic tested some loads from the 30s and found the results to be inconsistent; he felt from primer rather than powder degradation.
It's possible that those shells when fresh might have run higher pressures.