Experimental study on the influence of mounting and ground conditions on the shoulder force of typical machine guns

This study investigated the shoulder force and recoil displacement of machine guns and analyzed the influence of mounting and ground conditions. Distributed thin-film sensors were used to simultaneously measure the surface pressure at the shoulder area of the gun butt and the recoil displacement of the firearms. High-speed photography was used for the measurements. The shoulder force curve and the recoil displacement curve of the machine gun under different boundary conditions were obtained. The characteristics of the shoulder force and recoil displacement were analyzed by considering the "sliding" effect of recoil. Then, the influences of mounting and ground conditions were compared. An equivalent model for establishing the relationship between the shoulder force and the recoil displacement was constructed. The obtained results were compared with the experimental data. The experimental results indicate that the proposed method can simultaneously measure the shoulder force and recoil displacement. The shoulder force and recoil displacement are greater in the bipod condition than in the tripod condition; they are also greater in the cemented floor condition than in the sandbag-on-the-floor condition. The calculation results of the shoulder force-recoil displacement equivalent model agree well with the experimental results.