Look at different solvents on the market. Note the ones that remove lead, copper and plastic fowling. I use Birchwood Casey Bore Scrubber 2-in-1 bore cleaner. It removes everything. I get a good brass bore brush. On my Black Diamond, after I have it "clean" I then soak a patch and really coat the bore of the barrel with the solvent. I change over to the brush, dip that in the Bore Scrubber and start at the breech and push all the way to the muzzle. I make about 10 passes this way. So far I have never noticed a lead or anything buildup, and I shoot No Excuse Conicals also. After that run a couple dry patches through and they will come out clean also. Be sure and oil the bore afterward. I use Birchwood Casey Sheath, REM OIL or Breakfree CLP.