Sliver,
So far, ALL of many pitted barrels I have examined closely had more or less equidimensional pits, often with irregular edges. Generally these seem to be of consistant depth, which oil film method shows well. It is pitts that are deeper that make me wonder about slag inclusions, focused pitt formation, etc., things that can lead to especially weak areas and even holes. Steels from late 1800s and early 1900s are well known to have slag inclusion impurities and for these to become centers of electrolytic corrosion and perforation pitts. Bad news, those focused pitts!!
I have now and then seen what I thought was either streaks of leading or pitts that had formed under leading. I would expect they are wide enough for oil-film method to be useful. Some grooves or long scratches, lengthwise in barrels, make me think of something hard having been shot, like early steel shot, maybe in inadequate wad cups.
IF I were to see really narrow pits, not lenghtwise in bore, I might immediately wonder if there was a crack or long, smeared-out impurity (slag?) in barrel metal. Both just might cause me to reject that gun. If deepish pitts are not enough cause for concern, suspected cracks or extended impurities are even more.
Lars
Last edited by NiklasP; 01/26/08 07:38 PM.