I would always expect a bbl burst out around the forend to have had an obstruction unless absolutely proven otherwise. The other most likely cause (seldom encountered) is an internal flaw in the metal, actually more apt to be in the form of a seam in fluid steel, than in damascus.
As to the strength of the frame it will be more influenced by load than PSI's. The frame would much prefer a 3/4-7/8 oz load not exceeding 1200fps @ 9k+ psi than a full oz of shot @ 1300 fps, even if the psi's were held to 7.5K. Where max "Chamber Pressure" is important is "In the Chamber".
