a process for blow molding completely finished hollow plastic containers of biaxially oriented material and having a finished neck . a dual - diameter blow pin is positioned between separable mold sections and is movable along its longitudinal axis . a crammer sleeve is reciprocably disposed about the blow pin , and gripping jaws are positioned to close around the blow pin . one end of a heated tubular parison is positioned over a larger - diameter portion of the blow pin , and the parison is longitudinally stretched , axially orienting the material and causing the parison to neck down onto a smaller - diameter portion of the blow pin . the mold sections are closed over the stretched parison , the blow pin is longitudinally inserted to size the inside diameter of the neck opening , the crammer sleeve is inserted to cram axially - oriented material into the neck finishing cavity of the mold and to finish form the neck opening , and the tail surplus material is severed . upon separation of the mold sections , the crammer sleeve and blow pin are retracted , with the withdrawal of the crammer sleeve removing the severed neck surplus material . the neck forming portions of the mold sections are designed for easy insertion of the blow pin and the provision of a controlled volume of oriented material for the crammer sleeve .