The present disclosure relates to a telescoping assembly (102) of a drug delivery injector (100), comprising:a rotatable internal screw (208)；a pushing nut screw (204) nested together with the internal screw (208), whereby the pushing nut screw (204) is configured to move linearly with respect to the internal screw (208) upon application of rotation to at least one of the internal screw (208) and the pushing nut screw (204)；a pushing nut cover (210) attached to a plunger in a cartridge of the injector (100), the pushing nut screw (204) being retracted away from the pushing nut cover (210) in a transport configuration of the assembly, whereby there is a gap (402) therebetween； wherein a first few threads of the internal screw (208) are configured with increased friction against rotation in relation to remaining threads of the internal screw (208), thereby initially resisting linear movement of the pushing nut screw (204) through the gap (402) before the pushing nut screw (204) is linearly moved into a position to engage the pushing nut cover (210).
