220 Russian fire formed to 6mm ARC

[StoneHendge]

I would be real careful with the latter method. It's been years since I first fireformed 6x45 from 223, but there is (at a minimum) vigorous debate over the what happens when a .224 bullet is sent down a .243 barrel. Effects on barrel aside, I wonder if there is enough pressure to fully expand the case against your chamber walls.

* The only difference between .223 and 6x45 is the width of the case mouth.