I have about 100 Winchester brass for my 300 Win Mag and about half of them have a pressed pattern near the lip or top end of the neck which makes for a lot of chatter when chamfering and cleaning up the top. Does anyone know why this is on the brass or if I can trim it off to get to the clean brass?? This pattern is about 1mm in height and nearly touching the top edge. I am asking this question from the top of my head without measuring anything. Sorry for the lack of technical terminology or accurate measures for this question.