As it's Nationals season I am preparing my 4-year-old Shadow 2 for competition, for reference I think the gun ate around 15k rounds.
While doing a closer inspection I noticed that half of the barrel inside the barrel rifling grooves, there are some rough marks, like carbon. Hopefully, I captured it with my phone as I don't have a bore scope.
When I look at the chamber the grooves are clean.
I tried hitting it with a plastic pick, but nothing. I got the soft metal one and when I tried it I could see metal shavings
Can someone advise what is this?
I shoot factory FMJ ammo except in a few cases (recently) when I shot hand loads with cast bullets. Also, I clean my gun after every season.
Thanks in advance.