Unwind a Chore Girl or similar brass potscrubber. Wind 1 or 2 strands through and around the bristles on a bore brush, wet with Hoppe's or whatever, and scrub. It won't hurt the bore, the lead comes right out, and the price is right. Renew as needed.
Thanks and a tip o' the hat to Veral Smith...
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The Bill of Rights, and the Golden Rule are enough for civilized behavior. The rest is window dressing. Shoot carefully, swifter...