The Birchwood Plum Brown Barrel Finish Produces a rich, authentic, old style brown finish for original or replica firearms. Birchwood Plum Brown Barrel Finish is ideal for restoring antique guns, muzzleloaders and other metal antiques. A durable, protective and attractive finish that's simple to apply. Just heat metal with propane torch or other clean, convenient method and apply browning solution with swab. Immediate results - no waiting for old-fashioned slow rust process which can take weeks to finish.