A hydrostatic extrusion process and an apparatus therefor includes a mandrel and a stem which are movable independently of each other, and a seal block which is utilized for increasing the pressure of the pressure medium for performance of the extrusion operation of the billet. A supply device pre-disposes an extrusion die, a billet, pressure medium, and a seal block within a supply unit or sleeve and is capable of being moved from a position exterior of the extrusion apparatus station to a position corresponding to the extrusion station, and in this manner, the time period required for completing extrusion cycles is substantially reduced. Still further, a locking mechanism, including a locking slide and a locking plate, are operatively associated with the mandrel for controlling or limiting the axial movement of the mandrel so as to in turn control the loading and tensioning of the same in order to prevent damage thereto.