An automatic injection device configured for injection of a material stored in a syringe into an injection site, the syringe including a generally cylindrical storage container and a piston disposed therewithin, whose exact initial axial position within the container is not predetermined, wherein axial forward displacement of the piston in the container forces the material forwardly out of the container, the automatic injection device including at least one spring drive assembly operative, when actuated, to initially apply a first axial force to the syringe, thereby to axially displace the syringe in a forward direction, and thereafter, responsive to driving engagement with the piston, to apply a second axial force, substantially greater than the first axial force, notwithstanding the fact that the exact axial position of the piston within the container is not predetermined, to the piston, thereby to axially forwardly displace the piston relative to the syringe.
