"A Damascus barrel, like a chain, is no stronger than it's weakest element, whether it is a faulty weld, soft or brittle metal, or a hidden slag incursion. Proof firing did not always reveal these defects. Indeed, there is room for suspicion that proof firing could open these tiny fissures invisible to the eye. These would slowly be enlarged by corrosion and the strain of continued firing. This undoubtedly explains the instances in which Damascus barrels hold up for years with magnum loads, and then burst with a light field load. This treacherous sort of behavior should certainly be noted by those who use only black powder loads in such guns...... "DAMASCUS BARRELS- BEAUTIFUL BUT DEADLY" by Lee Kinnett Gun Digest 1972