US Patent 8925764 Piston securing device

A cartridge contains a storage chamber for a fluid filler material in which a piston can be movably received, wherein the storage chamber has a filling end and a discharge end and an inner wall extending between the filling end and the discharge end and the piston is displaceable in the storage chamber from the filling end to the discharge end along the inner wall to discharge the filler material from the storage chamber and the filler material can be enclosed in a sealing manner in the storage chamber by the piston. The piston is captively held within the inner wall by a projection provided at the inner wall in the environment of the filling end.