This article examines the utilization of the Plackett-Burman method to analyze the primary factors influencing the stability of the PKMS 7.62mm machine gun during firing. These factors include gun-mount mass, front leg length, position of contact between the buttstock and shoulder, shooter's biomechanics, stiffness of the ground platform, and uneven stiffness of the ground platform at the rear legs. The stability of the 7.62mm PKMS gun while firing is determined by three objective functions: vertical bounce of the gun body, horizontal bounce of the gun body, and displacement of the buttstock's location on the shoulder. The findings of this study indicate that the vertical bounce and shoulder point displacement are mostly affected by three factors: front leg length, shooter's biomechanics, and the unequal stiffness of the firing platform, as determined by the survey input parameters. Concurrently, the upward movement of the gun body is primarily affected by four factors: the length of the front leg, the gunner, the unequal stiffness of the ground platform, and the stiffness of the ground platform. The findings of this study will provide a foundation for optimization research in the field of firearm design and enhancement.