We designed a four-stage induction coilgun to launch a 1000-kg projectile. Although the coilgun system is optimized for launching a 1000-kg projectile, it is also capable of launching various lighter projectiles. In this article, we present an algorithm for optimizing the launch of a multipurpose missile with varying weights. We also analyze the performance of our coilgun system and evaluate the results of the algorithm using a simulation model. The algorithm is established using two types of Taguchi methods: LARGER-THE-BETTER and NOMINAL-THE-BEST. The charged voltage of the capacitor and the ignition position for each stage are considered as factors in the Taguchi method. While high efficiency is achieved by every stage except the first, the number of stages is minimized to ensure the simplification of the control system. This algorithm identifies the optimal conditions for achieving high efficiency, regardless of the weight of the projectile. The numerical simulation results demonstrate the effectiveness of the algorithm and the induction coilgun system for use in a multipurpose missile launcher.