The use of small-arms stability measures in combat shooting assessments

The acquisition of weapons at scale requires objective measures to discriminate between products and inform decisions. Testing of weapons commonly occurs on known-distance ranges in static positions at static targets using accuracy and timing as the main variables of interest. However, testing weapons in more representative environments may better show variations in ergonomic-related factors such as centre-of-gravity (CoG) changes. This study aimed to examine the utility of weapon accelerations as a measure of stability, understand how stability changes with repeated shots and the responsiveness to changes in the CoG. Eighteen soldiers shot 60 times under four conditions: an unweighted rifle and the addition of a mass fixed at three different positions. A weapon-mounted accelerometer captured the accelerations of the weapon 200 ms before shot release. Twelve stability measures were calculated and reduced via a principal component analysis. Three of these metrics were then assessed for changes over the shots and between the four conditions. Decreased stability occurred over the 60 shots for all conditions, suggesting increasing fatigue. Stability only differed between one pair of conditions with one metric, implying that stability can be maintained with the different weapon configurations.