I have a method that works for me, I do a regular cleaning with Hoppes and a brass brush, usually to get the bulk of the lead and the easy stuff. I then use liberal (excuse the Liberal word) amount of canola oil, yep the one you have in the Kitchen. I let a rag soaked in it sit in the barrel for a few hours or over night. The next day the lead and fouling comes out in chunks. You can use the left over oil for frying(just kidding).Experts say Fire Clean was just canola oil and that stuff was $18 an ounce.