The recent resurrection of Tonys thread re the 20 ga Clarke got me wondering about bulges again. Ive read (ie, Shotgun Technicana) that any dent must be repaired because a dent is a form of an obstruction and therefore dangerous. On the other hand, Ive read that many barrels with bulged barrels are safe to shoot, depending on whether the bulge is in a low or high pressure region. This brings me to my question that Im hoping an experienced gunsmith or metallurgist will try to answer. What to do with bulges close to the breech? Close to the breech is a high pressure area, a likely unsafe area for a bulge. Im assuming a bulged barrel in this area is unsafe to shoot, but is a bulge in this area amenable to repair? It seems to me that once the metal is actually stretched after reaching its elastic limit, its molecular structure is forever changed. Ive read on this forum that hammering down a bulge actually hardens the metal. Is the entire bulged area now competent since it is hardened after being hammered down? What about being more brittle since being hardened? Are theire faults in the hammered areas that would be prone to rupture or is the area now sound and 100% competent? How would one know for sure after repairing a bulge in a high pressure area if the repair is sound or prone to rupture? Im guessing electron microscopy looking for voids would be about the only way to tell for sure, but Im not a metallurgist. Id be interested in educated opinions. I have a friend who has a gun with this very problem, a ring bulge close to the forcing cone.
