I have an Swedish M42B that I have had for decades
Thought the the barrel was shot because it would never come clean
Was going to part it, but, I thought that I might as well soak the metal with KR oil and leave it
After a few days the barrel was leaking a black crud, so I sprayed oil into the barrel , it leaked more
In the end the barrel was clean and in excellent condition sharp rifling
So, try this it might help
Thought the the barrel was shot because it would never come clean
Was going to part it, but, I thought that I might as well soak the metal with KR oil and leave it
After a few days the barrel was leaking a black crud, so I sprayed oil into the barrel , it leaked more
In the end the barrel was clean and in excellent condition sharp rifling
So, try this it might help























































