Shouldered pre-fits work on premium actions that have tight enough tolerances so we can headspace them to the factory action. We can set headspace at our factory without your action.
Barrel Nut Style Pre-fits
Barrel nut style pre-fit. Bottom the nut up against the shoulder of the your barrel, then set your headspace. Once you've got that set torque your barrel nut down. This is our most common style of pre-fit.