A gas spring curve control valve for a adjustable-volume gas-pressurized device is described. The valve allows for selection from among at least four spring curves and can be packaged in small spaces/devices. In an exemplary embodiment of the invention, a rotary cam having grooves and lobes that interact with spring loaded ball bearings and an external adjuster knob are used to easily change the gas spring curve “on-the-fly” and with minimal user effort.