There seems to be comment about a known ring bulge, and at the same time we're thinking that there were inward dents at the same location on the barrel? I'd speculate that what ever caused the ring bulge, might not be ruled out as the cause of the crack?
Those dents don't seem to reflect on the outside of the barrel. Due to the appearance of the patina, maybe there was some striking and refinishing in the distant past? Though it appears pushed outward, could the 'dents' be formed by uneven tapping down of a bulge? Could the crack have formed or showed after a fair amount of use, time and wear passed?
