Abstract: A pump, comprising an inlet portion having an ingress channel, an outlet portion having an egress channel, a firing portion, and a manifold having a passage in fluid communication with the ingress channel, the egress channel, and the chamber. The firing portion includes a firing cylinder and a firing piston. The firing piston is capable of performing compression strokes and expansion strokes within the firing cylinder. The firing cylinder forms a chamber in which fluid is drawn during an expansion stroke. A high-pressure actuation device drives the firing piston during the compression stroke to expel a high-pressure jet of fluid from the egress channel. If an injector device is held proximate to flesh, the jet of fluid has sufficient pressure to hypodermically inject the fluid without a needle. The inlet portion, outlet portion, and firing portion of the pump can be rearranged on the manifold to conform to the design requirements for a variety of slap injectors.