Apparatus for extrusion-blow molding a bottle for assembly with metal can end

An extrusion blow mold for forming a plastic bottle having a radial flange suitable for roll-form attachment to a metal can end. The mold has a pair of confronting mold halves, each mold half including a body forming portion, a bottom pinch-off portion located below the body forming portion, a top block portion including a blow chamber located above the body forming portion, and a spin-ring forming portion located between the body forming portion and the top block portion. The spin-ring forming portion includes a thread ring insert and a cutter ring insert. The thread ring insert has an inside upper edge including an outwardly extending surface terminating in a step defining a lower surface and a outer edge of a radial flange. The cutter ring insert is positioned immediately above the thread ring insert. The cutter ring insert has a lower surface adjacent an inside edge defining an upper surface of the radial flange including a tapered inner edge extending upward and inward from the step. At least one of the thread ring insert and cutter ring insert includes a relief surface connected to a vent channel to permit gas to escape from the area defining the radial flange.