I use Lyman dies and the modified Lee mold, and, as previously mentioned, the sizer either doesn't size the cases quite small enough, or the expander plug is too large, so the bullet can easily be seated with hand pressure. I turned out a new undersize expander plug that doesn't really do anything other than apply a bell to the mouth. Although the bullet is still not as tightly gripped as I'd like to see, it worked well enough.