Clean black gunk from pitting on bowie knife

My name name is Denny and am currenty collecting knives to give to my grand son for his 18 birthday. I just found an old Bowie knife and want to clean it up for his collection.
The knife has some rust and pitting on it. The problem is that I know I can't get the pitting out but is there some way I can get the black gunk out of the pitting with out grinding it?

Thank You,
Denny

Sandblast or a wire wheel will do the trick nicely.
I would also suggest disassembling the handle down to the tang to prevent any damage to the hilt and handle. This will also give you a chance to put any protection on the tang of the blade.
If you do decide to go with sandblasting start with coarse and step down in grit just like with sandpaper. If you go with the wire wheel, you should be able to go to a coarse rouge right after the brush to give it a decent polish.

After you are happy with the state of the knife give it a good coat of oil, or go with bee's wax if it is a show piece rather than functional. If the handle is wood I would also suggest bees wax ⇦ on eBay or Amazon [affil link] rather than a commercial synthetic wax.