Reducing a wallthickness by .002" by filing shouldn't be something that would make a set of barrels unsafe in most cases. I'm not saying that's how to fix this, just trying to put things in perspective.
The total fix for a bulge is to remove the ribs and cold forge (beat with a hammer) the bulge down all the way around the bulge, polish the inside and outside, re-lay the ribs and reblue. If the ribs aren't removed, the bulge repair won't put metal back in the proper place between the ribs. Then you have a bulge on the side, under the ribs and not on the other side.
