Is this advisable? Wouldn't that thin down the barrel walls too much? Aesthetically it might be workable but would you trust it? I'm just speculating here & don't really know if that would be a safety concern or not. I know I have a Parker Hale No1 MkIII with a sporterized turned down barrel and it's safe so???? Guess it all depends how much material would need skinned off. Would hate to blow the end of the barrel right off. Who knows ..... maybe I'm just being paranoid.
I wouldn't turn down the bulge but that's me. IF I were to try to repair that I would try rolling it back to nominal diameter.