<p>To address the challenge of achieving rapid and precise ammunition delivery from the magazine under varying loads and vehicle tilt conditions, this paper proposes an efficient control strategy that integrates a novel finite-time disturbance observer (FTDO) with a new implicit Lyapunov function-based super-twisting sliding mode controller (ILFSSMC). First, a novel FTDO is designed to accurately estimate both system uncertainties and external disturbances affecting the automatic shell magazine, thereby significantly improving positioning performance. Theoretically, this observer requires only the disturbance to be bounded and involves adjustment of only one tuning parameter, thus substantially enhancing its practical applicability. Then, a novel ILFSSMC is designed to achieve effective suppression of residual disturbances and high-precision positioning. The proposed ILFSSMC marks a significant enhancement over existing ILFSSMC approaches, as it ensures finite-time stability while delivering improved performance in both transient speed and steady-state accuracy. Furthermore, based on an implicit Lyapunov function framework, this controller reduces the number of tuning parameters required, significantly improving its practicality for the magazine system. Experimental results demonstrate that the proposed strategy maintains fast and high-precision performance under varying tilt angles and load conditions, while comparative studies confirm its superiority over existing methods.</p>