Effects of rifle weight and handling length on shooting performance.

The effects of rifle design parameters on shooting performance were explored in this study. Twelve subjects, all right handed experienced marksmen, were recruited for the experiments. In the first part of the experiment, effects of rifle weight and handling length on aiming stability were examined in a simulated aiming exercise. Multiple responses of joint angles of the upper extremities, EMG data of selected muscles, center of pressure fluctuations, aiming point fluctuations and subjective preference were analyzed. It was shown that different rifle designs led to an alteration of rifle holding postures and muscle activation levels in order to maintain the system in balance, thereby affecting aiming stability. In the second part of the experiment, the relationship between aiming stability and shooting accuracy was examined in a live-fire study. Aiming fluctuations data of the same subject in the two experiments were highly correlated (r = 0.92-0.94, p < 0.0001). Significant high correlations between aiming fluctuations and shot group dispersions (r = 0.86-0.98, p < 0.0001) support the assertion that aiming stability and successful shooting performance are interrelated. A practical implication of rifle design trade-off was addressed in the paper.