If you have an old, bad boar brush, dip it into a little bit of gun oil and use it to put a protective coat of oil on your gun. The brush tips easily get into checkering, engraving, ventilated ribs, actions and other hard-to-get-at spots without over oiling. This may also work with badger, but I have never tried it.

Let's hear more uses the inventive members of this forum have found for their otherwise useless brushes.