I have seen cases from that rifle and think it does have a headspace problem, though perhaps not yet to the danger point.
There is an easy way to check. Cut a case in half lengthwise with a hacksaw. Look to see if there is a depressed ring of brass inside in the same place as the shiny area on the outside, indicating that the brass is thin at that point. If there is (and I think you will find there is), the case is being thinned from stretching due to excess headspace, not merely being marked by a rough chamber.
What happens in a rifle chamber is that when pressure builds up, the thin forward part of the case expands outward and seals against the chamber walls. This is called "obturation" and is what keeps that high pressure gas in its place, and not coming back at the shooter.
But the rear of the case is solid and cannot expand, so it tries to back up, stretching the case. This happens about all the time, with every rifle and ammunition. Normally, the case will not stretch beyond the elastic limits of the brass, but if the rifle has excess headspace that elastic limit is exceeded. That is what is happening here, as shown by the bright ring of stressed brass.
If the headspace becomes more excessive, the case will actually be pulled (or actually pushed) apart and the head will separate. At best, this results in a stuck case which has to be removed; at worst, high pressure gas is released into the action damaging the action and, perhaps, the shooter.
Is the rifle at the danger point? I don't know, but it is not right, IMHO. If the cases are discarded, the problem can perhaps be ignored, at least for a while. But reloading such cases will further stress the brass and hasten case failure.
Jim
