To clean lands of smeared lead that happens when cast bullet shooting, wrapping a copper brush with some copper wool strands from a copper wool pad removes chunks of lead at a time. No amount of cleaning with a copper brush would come close to removing caked on lead as fast.
This process literally will get large deposits of lead out in a few strokes. If the barrel is really bad, re wrapping again is required to expose more of the sharp edges of the strands. You only need a little bit, and wrap it tight so you maintain the diameter of the brush as close as possible. If the brush won't push through after wrapping take some wraps off.
I strongly suggest you try this, it will not damage your barrel. Examine the brush for chunks of lead each time you run the brush through.
If this does not work to expose the rifling underneath, I would think the rifling might be worn away, or very shallow to begin with.
I came in here to say the same.
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