You have to set the protrusion after the tip has been reworked, because you will lose a little once the tip has been re-contoured. Every quarter turn on the cocking piece is equal to .009". The firing pin will only penetrate the primer .025", so I always give slightly more for differences in headspace, .035" is enough for full ignition. Reducing the protrusion from the usual .055" will give you .020" more firing pin travel.