I use a heavy patch..denim etc, and a dowel.. use a mallet to drive as tight as a patch as possible down the barrel...this will remove lead quite well.
You can get leading with about anything at any velocity... rubbing a lead ball on anything, at any speed..you will see that a mark, from lead left behind, will be made... I would think that 150 year old lead would be mosly oxsidized by now??