Abstract: A method of forming a blowback cavity in a vial or similar cylindrical article comprises the steps of providing a cylindrical glass preform having a necked region and first forming an open blowback cavity adjacent the necked region and a relatively thin axially projecting terminal lip on the adjacent end of the preform and subsequently turning the terminal lip inwardly to form a radially extending face defining a mouth opening having a diameter smaller than the diameter of the blowback cavity.

Abstract: The invention provides a precision tooling machine for final finishing of a preliminary formed shoulder on the open end of a heated glass vial blank. The shoulder of the vial is heated and the vial is rotated and horizontally advanced between a pair of co-operating tooling jaws which are respectively mounted on support arms which are in turn rigidly secured to a vertically slidably support plate. The entire weight of the tooling jaws, the support arms and the support plate is effectively counter-balanced so that tooling jaw units may move without restraint to accommodate themselves to the vertical position of the particular vial passing between the tooling jaws. At the same time, one of the jaw units is freely laterally shiftable a slight amount relative to the other jaw unit so as to prevent the possibility of differential heating of the tooling jaws or their respective support arms causing a misalignment of one tooling jaw relative to the other tooling jaw.