Hydraulic cylinders are commonly used in mechanical systems to convert hydraulic energy into mechanical energy to realise linear motion where high forces and robust operation is required. They are used in truck mounted guns to support the outriggers or spades which transmitted the impulse forces resulting from firing to the ground to protect the truck suspension and chassis. The total stiffness of a hydraulic cylinder and the transmit stress waves are affected by its mounting direction. In this paper the effect of mounting position of cylinders subjected to impulse force from firing was studied. It was found that the direction of mounting plays a significant rule on stress waves effects acting on both cylinder rod and cylinder barrel when subjected to impulse force. Results show that mounting position of cylinder barrel load case is better than mounting position of rod load case to withstand the stress waves.