It is the expander ball dragging on the inside of the neck. You can reduce the feel a couple of ways. One is to apply lube in the inside of the neck, I used to use a Q tip to do about every 10th case. I finally broke down and bought a neck lube kit that has 3 of 4 brushes of different calibers and a well that they stand in that holds a dry graphite lube. After about 50 cases I put the lid back on and turn it over to charge the brushes again.
Some dies are worst than others at that scraping.
Al