I have found if I lightly coat both sides of my aluminum flashing with Turtle Wax (dries to a light film)
and then cut my strips, the checks pop out of my sizing die flawlessly. Certainly, there are other solutions
but this one won't contaminate powder or primer. THat wax dries white and a can of Turtle wax will last me
a life time for this purpose. I use it for cars so its not like the stuff sits just for this mission but if it did, one can
is many life times of supply.
Works for me.