Disclosed are plunger assemblies which include a plunger sleeve, a plunger rod and an axial protrusion disposed within an inner cavity of the plunger sleeve. Application of a distal force onto the plunger via the plunger rod causes the axial protrusion to contact and apply pressure to an engagement surface in the inner cavity. The engagement surface is configured to receive distal force from the end of the axial protrusion. This causes the plunger to elongate and slightly constrict, thus reducing break loose force and facilitating transition from storage mode to dispensing mode of the plunger.