I have a duv-41 , 1941 Germa 98k that has a dark dirty bore with pitting all the way down the bore. I've cleaned it and cleaned it and...
(you get the picture) and still it's a dark, dirty, pitted bore; but it still prints 3"-4" @ 100 yds with iron military sights and my 50+ year old eyes.
I am amazed how well it shoots considering the condition of the bore, so I just keep shooting it and cleaning it, and I don't worry about it any more.![]()