...I was able to clean the lead off with some Fitz metal polish and a cotton swab, but it's starting to remove the blue...
Keep the Flitz away from any blued gun, same with a dental pick. If you need to scrape lead or carbon fouling, use Hoppe's (or similar) and a short length of heavy copper wire flattened on one end. If that won't remove what needs to be removed, leave it.