Higbean,
I do 'em a lot faster than that with a drill motor and countersink. I mount the motor with countersink in a bench vise, and have two plastic trays, one with brass to be chamfered and the other empty. I turn the motor on, grab case from the first tub, touch the primer pocket to the spinning countersink, and throw the case in the empty tub.
Countersinks cost a few bucks at a hardware store.
