Improving launch efficiency is critical for electromagnetic railgun applications. Existing sequential control studies focus on scenario-specific optimizations but lack universal models for trigger strategy impacts. Energy feedback research remains limited with insufficient factor analysis. This work thus addresses efficiency through sequential control and energy feedback. For sequential control, we built an automatic triggering strategy using MATLAB/Simulink. It quantifies how excitation current parameters—current limit, trigger threshold, and module count—affect efficiency. Optimal operational intervals were identified under safety constraints. For energy feedback, our muzzle energy recovery scheme boosts initial energy utilization to 24.74% (a 6.2% absolute gain). Key findings demonstrate that lower residual-to-peak current ratios at muzzle exit degrade feedback effectiveness. Furthermore, high muzzle velocity inherently conflicts with high efficiency goals. Conversely, within defined operational ranges, fewer feedback modules enhance performance—a principle supported by our theoretically derived minimum-module formula. This research establishes theoretical foundations for railgun efficiency optimization.