Abstract: A piercing die assembly for punching a plurality of radially extending holes in a tubular member. The assembly having an open end for receiving a tubular member to be punched. The die assembly having structure for supporting the tubular member in a pre-punching position including radially inner and outer die walls for backing up inner and outer wall surfaces of the tubular member to be punched. A plurality of spaced radially movable punch assemblies are operatively connected with the die structure and having a series of radially movable punches. The punch assemblies having bearings positioned at radially outer ends of the punches and each bearing and its associated punch being radially movable simultaneously together. A vertically movable ring-shaped actuator member is positioned radially outwardly of the punches and is movable axially from a pre-punching position to a post-punching position.