The rotating chamber is expected to significantly benefit mid-caliber automatic guns with the high firepower-to-armament space ratio. However, the parallel index, which is a core component of the chamber system, tends to be flexible in rapid operation. This may cause the chamber prone to torsional vibration so that serious misalignment problems arise during ammunition loading as well as firing processes. In this context, an active control algorithm is proposed incorporating a reaction wheel as the actuator, suppressing only the residual vibration and optionally self-adapting the shooting rate to the actuator condition. For assessment of the idea, the entire system is mathematically modeled and then simulated in several cases. The comparative simulation results support that by the proposed method the chamber vibration can be reduced even to 6.5 percent at the expense of relatively small amount of actuator energy.