I recently test fired some slugs that were different from what I normally use. Started out with a shiny mirror clean bore. I fired off 7 foster type slugs followed by 4 rounds of birdshot. 12 gauge 20 inch smooth bore. After thoroughly cleaning with Hoppes # 9 and bore cleaner and scrubbing vigorously with a 12 gauge brass brush there is still a stubborn lead deposit around 1 or 2 inches long and about half way down then barrel. How do you slug shooters get the lead out of the barrel?