I have never had this problem so I could use some input. When I run my 7MAG brass through the dies I find some that telliscope or ripple in the neck area. I lube the neck with RCBS brass lube and all the openings have been chanferd to remove all dents inside and outside. When I place my Bullets in they all are Boat Tails eather Nosler or SSTs. the Brass is checked and the dies are lubed also.