The present invention relates to a cartridge holder assembly for a drug delivery device as well as to such drug delivery device and to a corresponding method of assembly, wherein the cartridge holder assembly comprises:a cartridge holder (14 40) adapted to receive a cartridge (12) to be filled with a medicinal product to be dispensed by the drug delivery device, wherein the cartridge holder (14 40) comprises at least one through opening at a distal end section to receive a piercing element (20) being adapted to penetrate a sealing septum (22) of the cartridge (12),a constriction member (26 42) being adapted to axially abut against the septum (22) and comprising a through opening (34 52) to receive the piercing element (20), wherein said through opening (34 52) is adjustable in diameter.
