You can knead a little turtle wax into a shop rag and let it dry for a few days.
Forever you can wipe loaded round bullets with it. It doesn't affect loads using either dry film coated(like moly) or uncoated bullets, because only the exposed bullet nose is being waxed. The bullet bearing remains as load developed.
For brass, I know of no tricks really. You don't want to leave behind any residue in chambers. I've been hoping someone would come up with a way to more or less anodize our brass to prevent tarnish.