I don't know how many rounds have been through it, I have personally only done around 500. It is a loaner from a family member to see if I want to go 9mm or not, and compare it to the P320 or other calibers. I have never inspected the bore this closely, I pull a bronze brush with CLP (I put the rod in through the muzzle end, attach the bronze brush on the camber end, and pull it from a handle that allows the rod to turn with the rifling), a nylon one, then patches until clean, then oil.
To me this doesn't seem like added material (lead, copper) but peeling/flaking. Any cause for concern for a range gun? I find $30 to $190 barrels (well, more for fancy stuff) as I don't want to return it in this state (I don't know if it happened while I have had it or not).
I want to blame my accuracy (lack of) on it, but I have been getting better, so I feel that is a me thing, not the weapon.