I saw the same gunsmith (Clovis LeJune) that Der Ami saw at work, this time though he put the bent shotgun barrel set between centers in his lathe and whopped it with a large black rubber hammer, hard. It wasn't mine, thankfully. He had some sort of a spiral wire device attached to a naked light bulb in his shop, and looked through the barrels at that device, put it back in the lathe, whopped it again, looked at it toward his device again, and pronounced it fixed. I guess his method evolved over time, but I do not know which method was first and which last.