That is a shame. Hard to say what happened. Unless there was a flaw in the barrel. is the bulge obvious on the outside? You can send the barrel out to a gunsmith I recommend to have the barrel sleeved and rifled to any twist rate you want. He may be able to mill off the bulge on the outside refinish the outside too.
Drop me a PM and I will give you his name and number so you can call him and discuss your issue.