Here is a response I got from them:

The chamber pressure for our 10-gauge, 2-7/8”, BGL107 loads is: 9,200 PSI



The chamber pressure for our 12-gauge, 2-1/2”, UGL125 loads is: 7,000 PSI



Neither of these loads is intended for use in shotguns having either Damascus or twist steel barrels, regardless of nitro-proof qualification.



I hope this information helps.



Shoot safely,



Ken Levin

Bismuth Cartridge Co.

Director of Operations