I recently rolled some of my .223 77gr. SMKs on a flat surface finding 60% of them have some run-out and 40% of them have, what I would call, a lot of run-out. I'm wondering where in the reloading process this is happening and what I can do to eliminate it. Could the sizing process be moving the neck out of alignment or is the bullet not seating straight? I tend to think the flaw is in the seating process. Any suggestions will be appreciated. Thanks.