Part of a variable recoil system of a gun, it is a spring-loaded valve through which recoil oil must flow during recoil; as the gun is elevated, the spring pressure is increased by means of a control arm; the valve thus offers greater resistance to the flow of recoil oil and the length of recoil is reduced; in a similar manner, depressing the gun decreases the spring pressure of the valve, with less resistance to oil flow and hence greater length of recoil.