Gunshot

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A gunshot from the Mark 45 gun 5-54-Mark-45-firing edit.jpg
A gunshot from the Mark 45 gun

A gunshot is a single discharge of a gun, typically a man-portable firearm, producing a visible flash, a powerful and loud shockwave and often chemical gunshot residue. The term can also refer to a ballistic wound caused by such a discharge.

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Multiple discharges of one or more firearms are referred to as gunfire. The word can connote either the sound of a gun firing, the projectiles that were fired, or both. For example, the statement "gunfire came from the next street" could either mean the sound of discharge, or it could mean the bullets that were discharged. It is better to be a bit more specific while writing however. "The sound of gunfire" or "we came under gunfire" would be more descriptive and prevent confusion. In the latter phrase, in particular, "fire" is used more (i.e. "under fire"), as both words hold the same general meaning within the proper context.

Gunfire characteristics

There are three primary attributes that characterize gunfire and hence enable the detection and location of gunfire and similar weapon discharges:

  1. A muzzle flash which occurs when superheated gases and incompletely combusted propellant residue are secondarily ignited upon contact with fresh ambient oxygen after being expelled out the gun barrel
  2. A muzzle blast which occurs when high-pressure gases within the barrel are suddenly released and rapidly expand when the projectile exits the muzzle and the bullet-bore contact that maintained the seal is removed. A typical muzzle blast generates a shock wave with a sound pressure level (SPL) of 140 dB or louder. [1]
  3. A whip-like “snap” or “crack” caused by the sonic boom that occurs as a projectile moves through the air at supersonic speeds.

Gunfire can be confused with other noises that can sound similar, such as firework explosions and cars backfiring. Gunfire noise propagation is anisotropic. The sounds may be heard at greater distances in the direction of bullet travel than behind or beside the gun.

Urban areas typically exhibit diurnal noise patterns where background noise is higher during the daytime and lower at night and the noise floor directly correlates to urban activity (e.g., automobile traffic, airplane traffic, construction, and so on). A firearm's muzzle blast may be masked by ambient noise during the daytime, but may be detected at greater distances during the quieter hours of darkness. A popular urban gunfire locator system typically uses six to ten audio sensors per square mile for trilateration. [2] [ failed verification ] (two or three per square kilometer)

A suppressor can be attached to the muzzle of a firearm to decrease the auditory signature of the high-velocity gases released from the muzzle when firing the weapon. The sound of firing is only decreased, however, and is still considerable. Suppressors attached to the muzzle will not reduce the sound of high velocity gases released from other locations, such as the gap between the cylinder and barrel of a revolver. A muzzle suppressor is similarly ineffective in reducing the snap of a supersonic bullet or the noise produced by the mechanical action of a self-loading firearm. Use of suppressors is rare in United States crimes. A 2007 study estimated unlawful suppressor possession was involved in only 0.05 percent (1 in 2,000) federal criminal prosecutions; and the suppressor was unused, but simply in the possession of the defendant for 92% of prosecutions involving a suppressor. [3]

See also

Related Research Articles

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<span class="mw-page-title-main">Bullet</span> Projectile propelled by a firearm, sling, or air gun

A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. They are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax; and are made in various shapes and constructions, including specialized functions such as hunting, target shooting, training, and combat. Bullets are often tapered, making them more aerodynamic. Bullet size is expressed by weight and diameter in both imperial and metric measurement systems. Bullets do not normally contain explosives but strike or damage the intended target by transferring kinetic energy upon impact and penetration.

<span class="mw-page-title-main">Muzzle brake</span> Anti-recoil gunbarrel attachment

A muzzle brake or recoil compensator is a device connected to, or a feature integral to the construction of, the muzzle or barrel of a firearm or cannon that is intended to redirect a portion of propellant gases to counter recoil and unwanted muzzle rise. Barrels with an integral muzzle brake are often said to be ported.

<span class="mw-page-title-main">Recoil</span> Backward momentum of a gun when it is discharged

Recoil is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force required to accelerate something will evoke an equal but opposite reactional force, which means the forward momentum gained by the projectile and exhaust gases (ejectae) will be mathematically balanced out by an equal and opposite momentum exerted back upon the gun.

<span class="mw-page-title-main">Ballistics</span> Science of the motion of projectiles

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<span class="mw-page-title-main">Flash suppressor</span> Firearm muzzle attachment that reduces the visibility of burning exhaust gas

A flash suppressor, also known as a flash guard, flash eliminator, flash hider, or flash cone, is a device attached to the muzzle of a rifle that reduces its visible signature while firing by cooling or dispersing the burning gases that exit the muzzle, a phenomenon typical of carbine-length weapons. Its primary intent is to reduce the chances that the shooter will be blinded in low-light shooting conditions. Contrary to popular belief, it is only a minor secondary benefit if a flash suppressor reduces the intensity of the flash visible to the enemy.

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<span class="mw-page-title-main">Gun barrel</span> Firearm component which guides the projectile during acceleration

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The .22 Long Rifle, also known as the .22LR or 5.6×15mmR, is a long-established variety of .22 caliber rimfire ammunition originating from the United States. It is used in a wide range of firearms including rifles, pistols, revolvers, and submachine guns.

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<span class="mw-page-title-main">Transitional ballistics</span>

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<span class="mw-page-title-main">Gunfire locator</span> System that detects and conveys the location of gunfire or other weapon fire

A gunfire locator or gunshot detection system is a system that detects and conveys the location of gunfire or other weapon fire using acoustic, vibration, optical, or potentially other types of sensors, as well as a combination of such sensors. These systems are used by law enforcement, security, military, government offices, schools and businesses to identify the source and, in some cases, the direction of gunfire and/or the type of weapon fired. Most systems possess three main components:

<span class="mw-page-title-main">Contact shot</span> Type of gunshot wound

A contact shot is a gunshot wound incurred while the muzzle of the firearm is in direct contact with the body at the moment of discharge. Contact shots are often the result of close-range gunfights, suicide, or execution.

<span class="mw-page-title-main">Muzzle flash</span> Light created by gunfire

Muzzle flash is the light — both visible and infrared — created by a muzzle blast, which is caused by the sudden release and expansion of high-temperature, high-pressure gases from the muzzle of a firearm during shooting. Both the blast and flash are products of the exothermic combustion of the propellant (gunpowder), and any remaining unburned powders reacting with ambient air. The size and shape of the muzzle flash is dependent on the combustion energy of propellant being used, the amount of combustible ejecta remaining, and any devices attached to the muzzle.

<span class="mw-page-title-main">Muzzle blast</span> Explosive shockwave from firearm muzzle

A muzzle blast is an explosive shockwave created at the muzzle of a firearm during shooting. Before a projectile leaves the gun barrel, it obturates the bore and "plugs up" the pressurized gaseous products of the propellant combustion behind it, essentially containing the gases within a closed system as a neutral element in the overall momentum of the system's physics. However, when the projectile exits the barrel, this functional seal is removed and the highly energetic bore gases are suddenly free to exit the muzzle and rapidly expand in the form of a supersonic shockwave, thus creating the muzzle blast.

The following are terms related to firearms and ammunition topics.

<span class="mw-page-title-main">Muzzle shroud</span> Gunbarrel attachment protective against burns and blast waves

A muzzle shroud, linear compensator, blast shield, forward blast diverter or concussion reduction device (CRD) is a sleeve that attaches to and extends beyond the muzzle of a firearm in order to redirect some of the noise and concussion, or shock wave, from the muzzle blast forward and away from the shooter, and other bystanders, behind and to the sides.

<span class="mw-page-title-main">Silencer (firearms)</span> Device which reduces sound intensity or muzzle flash on a firearm

A silencer, also known as a sound suppressor, suppressor, or sound moderator, is a muzzle device that suppresses the blast created when a gun is discharged, thereby reducing the acoustic intensity of the muzzle report and jump, by modulating the speed and pressure of the propellant gas released from the muzzle. Like other muzzle devices, a silencer can be a detachable accessory mounted to the muzzle, or an integral part of the barrel.

References

  1. ↑ Horman, B. Gil. "Sound Suppressors 101". American Rifleman. Retrieved 27 November 2013.
  2. ↑ Bradshaw, Tony. "Targeting the Source of Illegal Gunfire". Esri . Retrieved 27 November 2013.
  3. ↑ Clark, Paul A. "Criminal Use of Firearm Silencers" (PDF). Western Criminology Review. Retrieved 15 September 2016.
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