Cleaning- Help

[LegalPad]

Let me preface this by saying that I’m an idiot and new to this.

I left my musket with someone for around a week, and it rusted a lot. While cleaning the rust, there is black discoloration, seemingly raised on the gunmetal, that won’t come off. Am I stuck with this?

Thank you for humoring me.

 

[tenngun]

How are you cleaning?
Black stuff on the patch on the bore wipe or on the barrel?