The aims of this study were to assess postural risks associated with the current gun barrel cleaning method and to develop an ergonomic gun barrel cleaning method that could reduce such risks. The inner surfaces of gun barrels should be cleaned after use to maintain their firing function. The current method of cleaning gun barrels requires multiple soldiers to push and pull a long cleaning pole for 1–3 hr. Such motions require both hands to be raised to shoulder height. The current manual method and a newly designed automated method were compared in terms of safety and effectiveness. Postural risk assessments were performed using OWAS, RULA, and REBA. Results: The manual cleaning method involves the highest postural risk level (Action Category/Level 4), requiring immediate intervention, and exposes multiple soldiers to life‐threatening situations for a longer time during wartime. The postural risk associated with using the automated cleaning system was much lower (Action Category/Level 2). Once loaded into the gun barrel by a single soldier, the automated system takes approximately 20 min to complete cleaning. The automated cleaning method reduces musculoskeletal disorder risks associated with cleaning gun barrels and increases military power. The automated gun barrel cleaning method is an ergonomic solution that can be used for cleaning gun barrels within a short time without exposing soldiers to postural risks.