It seems to me that it was most likely the second borrower who was at fault. I would expect anyone to notice if a gun they were borrowing had two bulges before, during or after they shot it. It is a testimony to how strong those barrels were tha even after bulging they did not let go. Perhaps the shooter used to heavy loads at the end. If I borrowed it and did that to it I would be honor bound to buy it. You break it you buy it. Might be different if it were a long repaired stock but both barrels failing at once is operator error not gun defect. Wrong loads were used.