An auto-injector having a first sub-assembly. The first sub-assembly includes a housing, a chamber disposed within the housing and having proximal and distal ends, an inner surface and an exit aperture. The first sub-assembly also includes a stopper movably disposed within the chamber and having an outer surface in contact with the inner surface about its perimeter, and a port movable in relation to the housing and coupled to the chamber such that movement of the port causes a corresponding movement of the chamber and the exit aperture, relative to the housing, the port adapted to receive a container containing a fluid. When the port and the chamber are moved in relation to the housing, the stopper remains stationary with respect to the housing such that movement of the port causes movement of the exit aperture in relation to the stopper.
