Muzzle blast is the term used to describe the release of hot, high pressure gases from the muzzle of a firearm when it is discharged. Muzzle flash is the term used to describe the visible light of the muzzle blast. The blast and flash are caused by the combustion products of the gunpowder, and any remaining unburned powder, mixing with the ambient air. The size and shape of the muzzle flash is dependent on the type of ammunition being used and the individual characteristics of firearm and any devices attached to the muzzle (such as a muzzle brake or flash suppressor).
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Muzzle blast characteristics
The muzzle blast is often broken down into two components, and auditory component[1] and a non-auditory component[2]. The auditory component, the sound of the muzzle blast, is important because it can cause hearing loss or give away the gun's position, while the non-auditory component, the overpressure wave, can cause damage to items near the blast.
Sound
The sound of a gunshot can be loud enough to produce hearing loss, and with big guns such as artillery, that danger can extend outwards a significant distance from the muzzle[3]. Muzzle blasts can reach levels of 140 decibels, which can cause permanent hearing loss even with brief an infrequent exposure[4].
Overpressure wave
The overpressure wave from the muzzle blast of a firearm can contain a significant amount of energy; in artillery, the force of the muzzle blast can cause damage to surrounding structures and vehicles[5]. Residual pressures at the muzzle can be a significant fraction of the peak chamber pressure, especially when slow burning powders or short barrels are used[6].
Muzzle flash characteristics
Muzzle flash can be broken down into five distinct components.[7]
Muzzle glow
Muzzle glow is a reddish glow that is visible before the bullet leaves the barrel. Muzzle glow is created by superheated gases that have leaked past the projectile and have exited the barrel.
Primary, Intermediate, and Secondary flashes
The primary flash is caused by propellant gases exiting the firearm behind the bullet. Although amongst the brightest of the flashes, the heat of the primary flash dissipates quickly and thus is no longer visible. The intermediate flash is caused by shock waves created by the high speeds of the escaping gases and projectile, and appears as a reddish disc shape in front of the muzzle. Secondary flash appears farthest from the muzzle as a large white or yellow flame. Secondary flash is caused by the mixture of fuel-rich gases and oxygen in the atmosphere surrounding the muzzle. [8]
Sparks
Following the dissipation of the muzzle flash, partially unburnt powder or other heated materials can be ejected from the muzzle and appear as sparks.
Problems caused by muzzle flash
Muzzle flash is an inherent problem in most firearms. Due to its brightness, muzzle flash can temporarily blind the shooter, or give away the shooter's location, especially at night. Flash suppressors, commonly thought to be used to reduce visibility to the enemy, are in fact designed to reduce the muzzle flash from the shooter to preserve their night vision. Sound suppressors, in the process of reducing the sound of the muzzle blast, also reduce or eliminate the flash. Muzzle flashes create distinct signatures that can be located using infrared imaging technology. [9] In fact, technology is being developed to detect enemy muzzle flashes before the projectile reaches its target. [10] A famous case of possible infrared imaging of muzzle flashes occurred during the Waco Siege when aircraft equipped with FLIR cameras filmed the standoff and may have captured footage of government agents firing at unarmed civilians. [11]
See also
References
- ^ Muzzle Blast Sound Intensity, Firearm Sound Pressure Level
- ^ Blast Overpressure Studies. Nonauditory Damage Risk Assessment for Simulated Muzzle Blast from a l2Omm Ml2l Mortar System. (abstract)
- ^ Prediction of Standoff Distances to Prevent Loss of Hearing from Muzzle Blast
- ^ Hearing protection FAQ
- ^ Muzzle Blast Damage to Combat Vehicles (abstract)
- ^ internal ballistics
- ^ Tony DiGiulian, Muzzle flash, 14 August 2006
- ^ G. Klingenberg, Gun Muzzle Blast and Flash, 21 July 1988
- ^ Infrared sniper detection enhancement
- ^ [1]
- ^ The Waco FLIR Flashes
External links
- High speed photographs of shotgun muzzle blasts
