A pilot study of rifle and head kinematics during 0.50 caliber rifle firing.

Introduction: This study analysed rifle and head kinematics during firing, using automated motion tracking to quantify maximum rifle displacement, head displacement, and head acceleration. Methods: Six professional snipers participated in repeated firing trials under controlled conditions. Additional trials were performed for selected participants to show recoil conditions without a muzzle brake. Results: Rifle displacement ranged from 36.30 to 67.65 mm and head displacement from 25.86 to 44.55 mm with the muzzle break, whereas without the muzzle brake values increased substantially to 76.36-102.97 mm and 76.47-82.47 mm, respectively. Peak head acceleration showed a less consistent pattern, ranging from 3.71 to 8.62 g with the muzzle brake and 5.10-8.71 g without it. Interindividual variability was observed across all measures, suggesting an influence of participant-specific biomechanical and anthropometric characteristics on recoil transmission. Discussion: The findings from this pilot study indicate that the use of a muzzlebrake may reduce the translational recoil motion of both the rifle and theshooter, whereas peak head acceleration appears to be less affected. However, as the condition without a muzzle break was evaluated in only two participants with a limited number of trials, these observations should be considered preliminary and descriptive rather than conclusive. The results also suggest that individual biomechanical factors may influence recoil response, highlighting the need for larger, balanced studies to better understand the effects of muzzle brakes and their potential implications for ergonomics and shooting performance optimisation.