I shot "blanks" all day at a historical demo today, and when I got home, I pulled the lock, plugged the vent, and filled the 10 gauge smoothbore barrel with water. I left the gun to soak for about an hour while I did some chores. Now , I find that the vent plug leaked, and there are two nasty black lines running down the stock to the buttplate. I've tried to get them out while finishing the cleaning, but I'm not having much luck
Any suggestions on removing these stains?