Patent ID: 8343110

Claim:
An injection device comprising: a housing having a trigger projecting though the housing; a hypodermic syringe, including a syringe body terminating at one end in a hypodermic needle, said hypodermic syringe received within the housing, the syringe having a bore terminating at a forward end in a discharge nozzle and at a rearward end in a flared opening in which a discharge piston having a bore at a rearward end portion thereof is inserted; a drive element having a forward end consisting of a substantially flat edge region that is adapted to bear upon the rearward end of the discharge piston of the syringe and surrounds a projecting middle region which continuously tapers from the substantially flat edge region to a closed end neb and that is adapted to be received in the bore at the rearward end portion of the discharge piston; and an actuator a drive spring actuatable by the trigger for advancing the syringe from a refracted position in which the discharge nozzle is contained within the housing to an extended position in which the discharge nozzle extends from an aperture in the housing and for advancing the drive element so as to advance the discharge piston and discharge the contents of the syringe through the discharge nozzle.