a process and apparatus for the injection - extrusion blow molding of a hollow tubular plastic product useful as a liquid container or the like , and which includes the steps of injecting a predetermined amount of the thermoplastic resin into a tubular cavity so as to form a tubular first preform having a closed end , and then axially extruding the tubular first preform so as to extend the bottom end and form a hollow second perform . the second preform is then blow molded outwardly against the internal surface of a blow mold to form a bioriented finish product . the first preform may be heat conditioned prior to the step of axially extruding the same , and the blow mold may be provided with an axially moveable bottom wall which permits a finished product to be formed having a substantially uniform wall thickness .