The problem with a bulge similar to what you describe is the metal has stretched and is forever weakened. It can be pressed down but it has permanently lost its elasticity and beating the bulge down will not restore the strength. Had the damage been done near the muzzle where pressures are much lower a repair might be "safe" but not in the critical first few inches of the breech. Merrington for sleeving one tube!

John McCain is my war hero.