Abstract: A syringe including a barrel, a needle subassembly holder positioned in the barrel, and a needle subassembly positioned in the holder. The needle subassembly includes a needle hub releasably connected to the holder and a needle connected to the hub. Further, the syringe includes a piston slidably received by the barrel. The piston includes a piston body and a piston head having a releasable portion temporarily covering a hatchway. The piston also includes a valve positioned proximal of the hatchway and movable between blocking and passing positions. A user may push the piston distally beyond an injected position in which the piston head contacts the holder causing the holder to move distally and the hub to contact the barrel, causing the barrel to bow, thereby storing potential energy.

Abstract: A syringe including a barrel, a needle subassembly holder positioned in the barrel, and a needle subassembly positioned in the holder. The needle subassembly includes a needle hub releasably connected to the holder and a needle connected to the hub. Further, the syringe includes a piston slidably received by the barrel. The piston includes a piston body and a piston head having a releasable portion temporarily covering a hatchway. The piston also includes a valve positioned proximal of the hatchway and movable between blocking and passing positions. A user may push the piston distally beyond an injected position in which the piston head contacts the holder causing the holder to move distally and the hub to contact the barrel, causing the barrel to bow, thereby storing potential energy.