A reloadable injector (10) comprises a reusable power pack assembly (12) for multiple injection operations. The power pack assembly (12) includes an outer body (16) and an energy releasing assembly (18) disposed within the body (16). The energy releasing assembly (18) is capable of providing multiple energy releasing strokes. A disposable cartridge assembly (14) is engageable with the power pack assembly (12) and forms an injection assembly therewith. The cartridge assembly (14) includes a housing (88) in which a charge of medicament (90) and a needle (96) is contained. A plunger (94) disposed within the housing (88) for forcing the medicament (90) through the needle (96). The cartridge assembly (14) receives energy from the power pack (12) during one of the energy releasing strokes to enable the needle (96) to project from the protected position to an unprotected position from the housing (88) and to enable the plunger (94) to force medicament (90) through the needle (96).
