Swampman. The tradition Brit method is to use a low cut of Shellac in Alcohol so it is about the constituency of cream. Plug the muzzle with a cork then fill the bore to the top with the Shellac mixture then pour it out hang up the barrels and remove the cork and let the excess drip out, in doing so it will cover the places where the cork has been. To remove the Shellac re-cork and fill the bores with Alcohol let it stand for a while then swab the bores out with a cloth pull through soaked in Alcohol to remove the worst of the Shellac. Then use a cleaning rod with patches it may sound rather a long job but it is infact quite quick but sticky.
