THE CASE MOUTH WAS NOT DEBURRED. THIS MAY PLACE CHIPS OF BRASS IN THE SIZING DIES NECK, SCRATCHING THE BRASS. Lupua 30-06 brass. ANOTHER CAUSE If you get any black "soot" deposits, on you necks, be sure to clean it off before using the full length or neck sizing dies. The "soot" is carbon, the hardest substance on earth. It will scratch dies. Not sure if this RCBS die was subject to carbon, as the marks seem to be inside the neck also?? I have heard of the expander button getting brass on it, causing damage. Why not carbon also??