The initial focus of this paper is to determine the dynamic stability of a military vehicle under the effects of Active Protection System (APS) counter-measure launcher time variant firing loads. The detailed integrated finite element (FE) models of the vehicle chassis, turret and APS launcher assembly have been developed by using Altair/Hypermesh and Abaqus/CAE. Substructuring technique was used to generate the vehicle flexible body dynamic model, which was further coupled with non-linear suspension and track assembly in Adams Tracked Vehicle (ATV) toolkit and subjected to time variant firing load. Appropriate vehicle responses were observed to ascertain the platform stability under such firing influence. Subsequent emphasis was laid to validate the structural integrity of the existing launcher mounting assembly and thereby arrive at a suitable design configuration iteratively. Modal dynamic analysis was carried out on the modified launcher mounting assembly under the influence of time variant firing recoil loads in required directions. The von-Mises stresses were captured at critical locations of the modified mount structure and were observed to be within allowable limits. The dynamic variations of translational and rotational displacements at the launcher trunnion location were also captured. This detailed structural dynamic analysis methodology would provide very good technical guidance to the external ballistics team to assess the counter-measure firing accuracy. The flexible body dynamic analysis technique would enable assessing the vehicle structural dynamics and stability in an integrated environment. This study would establish a base platform even for future development of light military vehicles with APS.