How does removing more metal make it better other than making it easier to keep clean? And 3" sounds like it has already been cleaned up once. Any idea about the metal thickness at this area. Rule number one to me on doubles with suspect barrels in general and chamber in particular is that if they are suspect that are not to be shot until proven safe. Eyes, noses, hands and fingers are not trivial things to put at risk. The world is full of other safe guns.