I have some brand new .243 Winchester brass that is brand new that was purchased 6-7 years ago. The other night, I went to load some rounds and ran into an issue. As always, my first step is to run them through a Forster F/L sizer (with expanding ball in place) using Imperial wax. I mainly do this to round out the case mouth.

After performing the step above, I went to charge and seat and the seating was where I ran into an issue. I was seating 100gr Remington Core-Lokts and after seating, I noticed that the case mouth was too large to reliably hold the bullet in place. Therefore, just shaking the case would move the bullet. Where have I gone wrong here?

I have performed these same steps many times in the past and no changes have been made to my die. This setup has worked well using 85gr HPBTs and 87gr VMAX. I'm using a Forster Co-Ax press.