Unmanned Aerial Vehicles (UAVs) represent a serious threat to forward deployed forces of the United States Army. The defense against such threats is currently provided primarily by the Bradley Stinger Fighting Vehicle (BSFV). The problem addressed is how to evaluate the effectiveness of the BSFV against a UAV. This book develops a computer simulation methodology for modeling the capability of a gun system to engage a UAV. Specifically, a review is made of the BSFV, BSFV 25mm Ammunition, and UAVs. These reviews formed the basis for a computer simulation, coded in Common Lisp Object System (CLOS), modeling the characteristics of three objects: a Projectile, a Launcher and a UAV. Although assumptions were made to simplify the model, simulation runs demonstrated that the rate of fire and aiming system used for launching projectiles resulted in one or more hits in 125 out of 154 engagement sequences. These engagement sequences were against a UAV flying at constant speed and altitude in crossing and inbound/outbound flight profiles. While all data used in this simulation were unclassified, the methodology presented could be used for further classified study, potentially producing a lower cost means for determining the effectiveness of air defense weapons against UAV threats.