I am aproaching 30 years as a competitive cast bullet shooter.
There are three ways to resonably remove lead from a bore with chemicals; 1) the foul out, I prefer the 5 cent verson from the hardware store, Google it and it should come up. The principal componet is household amonia.
2) A product called RB-17 which is the only product I ever found that would remove lead from a comp chamber in an IPSC race gun with just a tooth brush. RB-17 was written up in Front Sight, the IPSC magazine, and is almost unbelievable in how well it works to lift and disolve lead. It is a gel that smells of amonia. It will not remove blue if properly used.
http://www.rb-treasures.com/product3.html
3) As mentioned the copper solvent version of Shooter's Choice will lift lead in a bore, but requires a long full bore soak of about a week.
Best,
Ed