It is generally held that gun barrels wear-out from erosion in the throat. The picture looks more like the physical damage caused by something harder than (or as hard as) the barrel steel, like the steel core of a barrel brush breaking and jamming into the end of the rifling. In short, the problem was not caused by a high round count...somebody jammed something into the muzzle of that rifle that should not have been put there (if that gun was not new). Or it was a manufacturing defect...if the gun is new. If that defect is only near the muzzle, then as someone posted, the affected portion can be cut off and the barrel recrowned.Discouraging, round count bore age ?
I'm no expert, but that looks like tool chatter to me. The QC never should have passed that one...
Call, then send it to Remington??