I am new to the PS90. I have only owned one for about a week, but I have made an interesting discovery. When I chamber a round in the rifle and eject it without firing it, there is a little ring on the brass right in front of the shoulder. Is this something every PS90 does or do I just have a bad rifle/batch of ammunition? The round on the left is fresh out of the box, and the one on the right has been chambered. Any ideas?