Abstract: A necking-out tool for forming projecting cylindrical nipples or necks on the circumferential wall of a pipe container or the like. The tool has a screw plug having a hook-shaped forming head and a thrust sleeve provided with a coaxial downholder flange for cooperation with the forming head and the screw plug. The thrust sleeve also has a hollow cylindrical interior corresponding to the contour of the forming head for the reception of the formed nipple or neck. A non-rotatable, telescopic guide means is associated with the thrust sleeve for mounting a torque converter on the screw plug.