A unitary barrel, chamber and bolt region for a firearm is manufactured from a single piece of metal stock so as to precisely and consistently meet headspace requirements. A single piece of metal stock having a bore centerline is successively reamed based on a common datum to achieve precise headspace compliance. The unitary assembly is then profiled, again based on measurements from the datum, to provide a unitary barrel, chamber and bolt region without any form of juncture, headspace or harmonic limitations.