A reusable cartridge piston for use with film bag cartridges comprises a piston base, an intermediate portion and a piston head. An extension axis extends from the piston base through the intermediate portion and through the piston head. The piston also includes a lip sections extending radially outwardly with respect to the extension axis from a sidewall of the piston head, the piston base and the piston head being spaced apart from one another by the intermediate portion, with a gap between the piston base and the lip sections. The lip sections are respectively spaced apart from one another by slits formed between two neighboring lip sections, with the slits extending in a radial direction with respect to the extension axis of the piston. The piston base, the intermediate portion, the piston head and the lip sections are formed as one piece.