Abstract: This paper presents the synthesis of the lever arm of a gun positioning system in main battle tank (MBT). The main gun in any MBT is controlled by a gun positioning system (GPS). Most of the contemporary MBTs use a hydraulic actuator as a drive for elevation/depression of the main gun. The Gun Positioning System (GPS) can be idealized as a four-bar mechanism. The position of the actuator mounting decides the link dimensions and hence the variation of force during elevation and depression. Since the gun position varies from 20 degrees (elevation) to 9 degrees (depression) for the case under consideration, the force required to move the gun varies during elevation and depression due to change of length in the links of the mechanism. In order to improve the system performance it is essential to minimize the variation in the input force with respect to the gun position. The problem has been solved using analytical method and with a virtual prototyping approach. The results obtained are compared between the two methods. The virtual prototyping approach provides effective solution with 3D visualization and hence can be pursued.