Abstract: A metering pump including a pump body having a bore for receiving a flowable composition to be dispensed, feed inlet means communicating with the bore, and spaced outlet means including a check valve, for discharging the composition. A pressure chamber is defined intermediate the pump inlet and outlet. The chamber has an inlet, and an outlet communicating with the pump outlet through the check valve. A piston is mounted for axial reciprocation in the bore between a first position at which the piston is withdrawn from the pressure chamber inlet, and a second position at which the piston passes at least partially into such inlet. The pressure chamber inlet is bounded by sealing means including an annular sealing surface which converges in the direction of the pressure chamber, to a diameter less than that of the piston, whereby the surface may slideingly engage and seal with the piston upon the latter entering the pressure chamber.