[berkmberk1]

I don't think its fire damage. Its confined to the underside of the barrel in an area roughly 4" long x 1/2" wide. You don't even notice it unless you turn it over and look. It looks like it MAY have been severely rusted and it was removed mechanically quite some time ago, as even this bunged up area now blends perfectly with the patina of the weapon. As long as some of these old war horses lingered in forgotten drawers, trunks, tool boxes, it could have been laying on something that was perpetually damp....I don't know. But it doesn't look like heat to me. Unfortunately, photographs don't really represent 3D that well.