Various embodiments of drug delivery devices and methods of assembling such devices are provided. In one embodiment, a drug delivery device for dispensing medicament comprises a medicament cartridge, wherein the cartridge comprises (i) a distal end, (ii) a proximal end that is opposite the distal end along a body axis of the cartridge, and (iii) a movable piston arranged substantially at the proximate end of the cartridge. The drug delivery device further comprises a piston rod having a distal end for axially moving the piston in the distal direction during dispensing of a set dose of medicament, wherein a relative axial distance between the distal end of the piston rod and a proximal face of the piston is set during assembly of the drug delivery system. The relative axial position between may be set such that the piston rod and the proximal face of the piston abut each other.
