Figure adapted from Rasmussen et al 2009, Figure 9. The peak levels of the N-wave and shock wave are indicated with inverted triangles. The N-wave will start at the trajectory of the bullet and radiate cylindrically outwards from that line (See Figure 1).Īn example of an N-wave preceding the blast wave. If the bullet is accelerated to supersonic speed, the waveform observed down range will include a ballistic N-shaped wave (N-wave) in addition to the muzzle blast. Depending upon the ammunition characteristics, the projectile may be accelerated beyond the speed of sound in air thus breaking the sound barrier. After the projectile exits the barrel, the gases and unburnt propellant follow and produce what is called the muzzle blast. The primer ignites and combusts the powder, producing a larger volume of gas that forces the projectile out of the barrel. The trigger releases a firing pin that strikes a cartridge containing a primer, powder, and the projectile. The pull of a gun trigger initiates a chain reaction of events that result in one or more projectiles being fired down range. Limiting the time or number of rounds or the type of ammunition that a person may fire in a given training session is an administrative control. Firearm suppressors are an engineering noise control. ![]() However, the standard for industrial hygiene practice has been to follow a hierarchy of controls, beginning with eliminating or replacing the process that produces the exposure, then moving to engineering or administrative solutions to minimize the exposure, and then finally relying on personal protective equipment as a last resort. The most common approach to protecting the shooter and bystanders from the high-level impulse exposures has been to provide personal protective equipment - hearing protection devices (HPDs). The impulses from gunfire present a significant hazard to the hearing of the shooter and nearby shooters or bystanders. 30 caliber rifle with a muzzle brake ( Murphy et al 2012). 22 caliber rifle to well above 175 dB peak SPL for a. ![]() Peak sound pressure levels have been reported for small caliber rifles, pistols and shotguns ranging between 140 decibels peak sound pressure level (dB peak SPL) for a.
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