I have had a few expander plugs that allowed the bullet to move after being seated I took them out and reduced their diameter by a thousandth of an inch or so and that's how the problem giving them much more neck tension because of a smaller amount of expansion

As to a roll crimp for a max load of 296 or H110, I always use the Lee factory crimp die that applies a collet crimp to the brass

This crimp is absolutely fantastic and it will even work on projectiles that do not have a cannelure

__________________
"Acta non verba"