This paper describes the lumped mass parameter model of a pilot valve and taper rod-type compounded damping device used for high-speed and high-loading applications such as heavy artillery guns. The modelling of pilot valve and fluid interaction has been described by Euler equations and Laplace equations of potential flow in cylindrical polar coordinates for the axisymmetric situation. The viscosity effects in the model have been accounted through the inclusion of the damping term in the equation of motion of the pilot valve. The model presented has been experimentally validated using a test rig which is capable of simulating the firing impulse in the case of an artillery gun. The pilot valve results in a logarithmic variation in the orifice area of the damper leading to mechanical implementation of fault tolerance in the damper.