If you shoot a lot of pistol ammunition there is a good chance you will shoot cast lead bullets out of your gun at one time or another. Cast bullets can save you a lot of money. Unfortunately, when you use commercially cast bullets they can leave lead in your barrel that is hard to remove. This is a procedure to remove lead out of barrels that works very well.
A solution of 50% hydrogen peroxide and 50% white vinegar reacts with lead and eats any lead in your barrel within 2-3 minutes. It is important that you plug off one end of the barrel and fill the barrel up all the way with the solution. Only let it set in the barrel for 2-3 minutes and then dump it out and flush the barrel out with water. Follow this by a dry patch through the barrel followed by a brush with solvent on it. Patch out the excess solvent and you are done. You can repeat the process if there are stubborn deposits that won’t come out on the first try.
The solution used in this process can cause damage to your barrel if it is exposed for long periods of time; it can also damage blueing on chrome moly barrels. The remaining solution that comes out of the barrel does contain lead and is poisonous.