A method of assembling a pivotal bone anchor assembly with tooling includes positioning a retainer and a pressure insert within a central bore of a receiver, uploading a capture portion of a bone anchor through a bottom opening and into the retainer to cause the retainer to first widen within an expansion portion of the central bore to receive the capture portion and then to close around and secure the capture portion while providing for pivotal motion of the bone anchor relative to the receiver, and downwardly deploying the retainer and the pressure insert within the central bore with the tooling until an outer surface of the retainer engages a narrower engagement portion below the wider expansion portion to impede repeat widening of the retainer, and the pressure insert comes into forced interference engagement with interference wedging surfaces of the central bore to inhibit the pressure insert from moving back up within the receiver.