Yesterday I took my Spencer in 44-40 to the range and shot 100 rounds through it. I'm not casting .429 bullets yet so I bought some cast bullets. They are a bit undersized so accuracy suffered and leading was an issue.
I got the gun home and ran dozens of patches of Shooters Choice, Kroil, Sweets, etc through the bore. All this did was make the lead look real shinny.
So I remembered the advise of Gun Turpentine and I had some. Took a nylon brush, wrapped it with a layer of paper towel and then a bit of "Chore Boy" copper pot scrubber fibers. Stuck it into the bottle of gum turpentine until the paper towel was saturated and ran it three times down the bore.
Amazing how much lead showed up on the Chore Boy and the barrel was sparkling clean.
Gum Turpentine is my new friend!