I use the RCBS Trim Pro motorized, with 3 way cutters and a micrometer dial. It measures off the flat cartridge base, like in the "trim to length". If you have a CH trimmer, as I also do, with chamber type case holders, you can flip the case first then square the base of new brass, and then you trim to length, uniform the pockets, debur the flash hole, fire form and for match brass, segregate by H2o capacity. If I see real uneven neck thickness, I outside turn the necks only to uniform the necks, leaving a hair of unturned brass the full neck length. It is a one time prep, except the trim when or if the brass grows.
