Shooter-Experienced Blast Overpressure in .50-Caliber Rifles

BACKGROUND: Increasingly, military and law enforcement are using .50-caliber rifles for conflict resolution involving barricades, armor, vehicles, and situations that require increased kinetic energy. Consequences to the shooter resulting from the blast produced while firing these rifles remain unknown. We measured blast overpressure (OP) and impulse across various positions, environments, and weapon configurations to evaluate blast exposures to shooters. METHODS: Two separate, multiday, .50-caliber rifle training courses were evaluated to understand the blast exposure profile received from various tactical training scenarios, such as different firing positions (e.g., standing, prone, seated, kneeling) and locations (e.g., inside and atop vehicles, inside buildings, on hard/soft surfaces) across a variety of .50-caliber rifles with various barrel lengths, muzzle devices, and ammunition. Blackbox Biometrics, Generation 6, gauges were placed on operators to measure incident blast exposure. A total of 444 rounds fired from various .50-caliber rifles were evaluated to determine what OP was received by 32 different shooters. RESULTS: Our findings indicate OPs >4 psi are common and that muzzle devices are critical to blast exposure. Shooting positions closer to the ground experienced higher OP and impulse than did other positions. Suppressors mitigated blast effects well. CONCLUSION: When resources and operational parameters allow, suppressors are recommended, as are positions that move the shooter farther from reflective surfaces (standing preferred) to effectively reduce blast exposure. These shooter positions may require the use of supplemental rifle rests/tripods to provide sufficiently stable firing platforms from the standing position.