A dummy block for a metal extrusion press includes: a generally cylindrical base having a forward surface and an outwardly extending circumferential flange; an expandable collar coupled to the base, the collar having an inwardly extending circumferential rib abutting the circumferential flange; a plunger disc seated against the forward surface of the base and accommodated by the collar, and a plunger shaft extending through the plunger disc and coupled to the base.