Take 1 cast (preferrably swaged) lead bullet,
1 wooden dowel that fits the bore,
1 medium sized or mallet of your chioice and go to town.
Swaging the barrel is the most accurate way.
make sure the dowel is long enough that you don't hit the end of the barrel with the hammer.
It'll make you sick if you flatten teh crown on the muzzle!
PS-this only works with cast or swaged bullets. The 240 Hornady lead work real well as they are swaged and not cast(much softer)!