Well 200 times with wire brush and 200 with J.B.BORE paste ..nothing .looks like a knife mark perfect circle with opening and 1 spot about 1/8 long chewed in real bright silver look with light on area.its about 2 inchs in from outside of muzzle...

still am stumped why its 2 inchs in ..what could have made circle like knife with some off it ..only shot maxi-balls and very few roundballs ..only thing down barrel has been short starter/ram rod over 45 years ..What could be so strong to cut into metal is beyond me and 2 inchs from outside?no way the maxi-ball could stop in that area when being pushed in and cause mark ..why would lead only build up in one spot in circle like knife cut ..I am lost on this and wore out pushing a brush in that many times..cut mark goes from lands across into grooves not just on lands...