Something that can, and will help keep your bullets in the cases. Check the expander ball for size. Most of the time the factory gets them right, but not always. (.001"-.002") under nominal bullet diameter) A trick I learned from Brian Pearce, is to reduce the size of the expander ball to at least .004"- .005" under bullet diameter. It works! Even on extremely hard recoiling rounds the bullets stay in place if seated this way, along with a proper crimp. It doesn't cause an ugly buldge in the brass either.