I have a savage arms .308 with a stainless steel barrel. I noticed after cleaning it, alot of wear and scratches on the inside of my barrel near crown. I also noticed whst looks like to be rust? Correct me if I'm wrong but I thought stainless didn't corrode. Is this any cause for worry orvis this normal wear? I am a fairly new gum enthusiast and still a green horn so any advice would help greatly. Picture of barrel attached.