A method of assembling a pivotal bone anchor assembly with tooling includes applying the tooling to a receiver assembly that includes a receiver having a central bore, and a retainer and a pressure insert secured within the central bore. The method also includes 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. The method further includes downwardly displacing the pressure insert within the central bore with the tooling until an outer surface of the pressure insert comes into forced interference engagement with interference wedging surfaces of the central bore, with the pressure insert thereafter being inhibited from moving back up within the receiver.