How 'bout using Proof Loads??
1933 lawsuit against Remington Arms related to the burst barrel of a Baltimore Arms Co. shotgun after using a Nitro Club marked Proof Load.
https://books.google.com/books?id=7p...C&pg=PA120&lpg
https://books.google.com/books?id=7p...C&pg=PA127&lpg
The “maximum commercial load” was described at “5 long tons or 11,200 psi” (calculated long tons/sq. Inch X 2240 = PSI)
The proof load was “7 1/2 long tons or 17,800 psi”.
1936 testimony by W.A. King, Parker Gun Co. regarding a barrel burst, likely a 20g shell inserted before a 12g
https://books.google.com/books?id=jU...J&pg=PA802&lpg