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Bulletproof vest

From Academic Kids

A bullet resistant vest – also called body armour (U.S. body armor) – is an article of protective clothing that works as a form of armour to minimize injury from being hit by a fired bullet. They are commonly worn by police forces and the military.

The above name is somewhat of a misnomer since most such protective vests are of little or no protective value against rifles regardless of the type, style, materials or caliber of the rifle ammunition (ammo) or even against handgun caliber ammo fired from a rifle. (The exception is the common .22 LR, which can usually be stopped by these vests even when fired from a rifle.) These vests are generally protective against handgun ammo fired from handguns--again, regardless of type, style, materials or caliber of the handgun ammo.

Some types of vests may be augmented with metal (steel or titanium), ceramic or polyethylene plates that provide extra protection to vital areas. These "trauma plates" have proven effective against all handguns and some rifles, if the bullet actually hits the plate. These types of vests have become standard in military use, as advances in ballistic technology have rendered kevlar-only vests ineffective - The CRISAT NATO standard for vests includes titanium backing. Some vests are also designed to protect against knife attacks as well. This is done by coating the outer surface of the vest with tiny crystals of a sandpaper-like material or hiding a very thin plate of resin hardened glass-fibre sheet between the kevlar layers. This is important for the safety of law enforcement and prison guard personnel.

The most recent U.S. military-issue body armour, the Interceptor Multi-Threat Body Armor System issued in the late 1990's, has small-arms protective inserts made of ceramic which can stop, shatter, and catch 7.62 mm rifle rounds.

A vest does not protect the wearer by deflecting a bullet. Instead, the individual layers of material catch the bullet and spread its momentum over a larger portion of the body, deforming the round and hopefully bringing it to a stop before it can penetrate into the body. While a vest can prevent a bullet from penetrating, the wearer can still be affected by the kinetic energy of the bullet, with results ranging from bruises to serious internal injuries.

Contents

History

The oldest bullet-resistant fabric vests were made from silk. These rather expensive vests (often costing US$800 each in 1914) were capable of stopping some slow rounds from black powder guns. On June 28, 1914, Franz Ferdinand, Archduke of Austria, heir to the Austro-Hungarian throne was wearing such a silk vest, but nonetheless died when shot in the neck above the vest with a .32 ACP bullet fired by Gavrilo Princip using a handgun, starting a chain of events that quickly escalated into World War I.

During the late 1920's through the early 1930's, the criminal element in America began wearing less-expensive vests made from cotton padding and cloth. These early vests were capable of generally protecting against handgun bullets such as .22, .25, S&W .32 Long, S&W .32, .380 ACP, and .45 ACP traveling at slower speeds up to approximately 1000 ft/s, with the outcome that the .38 Special and .357 Magnum bullets were developed for US Federal Agents to counter the organized criminal element members and overcome their vests.

A more modern "flak jacket" was developed in World War II from nylon fabric but was only capable of stopping flak and shrapnel, not the .38 Special or .357 Magnum bullets.The original vest in World War II was the M-12 (Chriss U.S., 2002), which were “too heavy to be worn by infantry, and did not offer adequate protection from high-velocity rifle bullets” (Military, 2004). To combat this problem, in the Korean War the military came out with a new vest called the M-1951 (Chriss Body, 2002), “a vast improvement on weight, but the armor failed to stop bullets and fragments very successfully” (Military, 2004). For these reasons, Kevlar came into the picture. But Kevlar too had its failures because if “large fragments or high velocity bullets hit the vest, the energy could cause life-threatening, blunt trauma injuries” (Military, 2004). So they came out with the Ranger Body Armor, again it was an improvement over the previous armor but still had it's flaws like “it was heavier then the anti-fragment armor already worn by the infantry and offered less protection” (Military, 2004).

The newest vest is the Interceptor and it has its' flaws but protects the wearer from most lower to mid velocity threats. Modern bullet-resistant vests made from Kevlar were tested by United States police forces in 1975. Since then several new fibers for bulletproof fabric have been developed besides Kevlar, such as DSM's Dyneema, Akzo's Twaron, Toyobo's Zylon (now controversial, as new studies report it that degrades rapidly, leaving wearers with significantly less protection than expected (http://www.policeone.com/Zylon/)), or Honeywell's GoldFlex. These newer fibres are advertised as being lighter, thinner and more resistant than Kevlar, although they are much more expensive.

Performance standards

Both the Underwriters Laboratories (UL Standard 752) and the United States National Institute of Justice (NIJ Standard 0101.04 (http://www.nlectc.org/pdffiles/0101.04RevA.pdf)) have specific performance standards for bullet resistant vests. The US NIJ rates vests on the following scale against penetration and also blunt trauma protection (deformation) (Table from NIJ Standard 0101.04 (http://www.nlectc.org/pdffiles/0101.04RevA.pdf)):

Armor Level Protects Against
Type I
(.22 LR; .380 ACP)
This armor protects against .22 caliber Long Rifle Lead Round Nose (LR LRN) bullets, with nominal masses of 2.6 g (40 gr) impacting at a minimum velocity of 320 m/s (1050 ft/s) or less, and .380 ACP Full Metal Jacketed Round Nose (FMJ RN) bullets, with nominal masses of 6.2 g (95 gr) impacting at a minimum velocity of 312 m/s (1025 ft/s) or less.
Type IIA
(9 mm; .40 S&W)
This armor protects against 9 mm Full Metal Jacketed Round Nose (FMJ RN) bullets, with nominal masses of 8.0 g (124 gr) impacting at a minimum velocity of 332 m/s (1090 ft/s) or less, and .40 S&W caliber Full Metal Jacketed (FMJ) bullets, with nominal masses of 11.7 g (180 gr) impacting at a minimum velocity of 312 m/s (1025 ft/s) or less. It also provides protection against the threats mentioned in [Type I].
Type II
(9 mm; .357 Magnum)
This armor protects against 9 mm Full Metal Jacketed Round Nose (FMJ RN) bullets, with nominal masses of 8.0 g (124 gr) impacting at a minimum velocity of 358 m/s (1175 ft/s) or less, and 357 Magnum Jacketed Soft Point (JSP) bullets, with nominal masses of 10.2 g (158 gr) impacting at a minimum velocity of 427 m/s (1400 ft/s) or less. It also provides protection against the threats mentioned in [Types I and IIA].
Type IIIA
(High Velocity 9 mm; .44 Magnum)
This armor protects against 9 mm Full Metal Jacketed Round Nose (FMJ RN) bullets, with nominal masses of 8.0 g (124 gr) impacting at a minimum velocity of 427 m/s (1400 ft/s) or less, and .44 Magnum Semi Jacketed Hollow Point (SJHP) bullets, with nominal masses of 15.6 g (240 gr) impacting at a minimum velocity of 427 m/s (1400 ft/s) or less. It also provides protection against most handgun threats, as well as the threats mentioned in [Types I, IIA, and II].
Type III
(Rifles)
This armor protects against 7.62 mm Full Metal Jacketed (FMJ) bullets (U.S. Military designation M80), with nominal masses of 9.6 g (148 gr) impacting at a minimum velocity of 838 m/s (2750 ft/s) or less [provided the projectile hits the hard trauma plate insert]. It also provides protection against the threats mentioned in [Types I, IIA, II, and IIIA].
Type IV
(Armor Piercing Rifle)
This armor protects against .30 caliber armor piercing (AP) bullets (U.S. Military designation M2 AP), with nominal masses of 10.8 g (166 gr) impacting at a minimum velocity of 869 m/s (2850 ft/s) or less [provided the projectile hits the hard trauma plate]. It also provides at least single hit protection against the threats mentioned in [Types I, IIA, II, IIIA, and III].

Bomb disposal officers often wear heavy armor designed to protect against most effects of a moderate sized explosion, such as bombs encountered in terror threats. Full head helmet, covering the face and some degree of protection for limbs is mandatory in addition to very strong armour for the torso. An insert to protect the spine is usually applied to the back, in case an explosion blasts the wearer. Visibility and mobility of the wearer may be severely limited.

In terms of Kevlar, a IIA vest has around sixteen layers and a IIIA vest around thirty layers.

German standards allow for bullet impact depression of 20 millimeters on the mannequin's wax body under the vest; US standards allow for more than twice that (44 millimeters), which can be potentially lethal.

In addition, there are vests available for police dogs which offer a measure of protection for the animals.

A vest's material must not get wet, because it will lose its protective capability until dry again, or in some cases be permanently degraded (water acts as a lubricant, helping the bullet slip through between the fibres; ions may also weaken the structure of the fiber, see Kevlar for details). Most bulletproof vests have panels in sealed enclosures, but waterproofing is usually not perfect.

Legality

18USC931 Provides that: (a) In General.— Except as provided in subsection (b), it shall be unlawful for a person to purchase, own, or possess body armor, if that person has been convicted of a felony that is— (1) a crime of violence (as defined in section 16); or (2) an offense under State law that would constitute a crime of violence under paragraph (1) if it occurred within the special maritime and territorial jurisdiction of the United States.

Many states have criminalized the use of body armor by convicted felons. In February of 1999, the late Russell Jones a.k.a. "Ol' Dirty Bastard" was arrested in California for possession of body armor by a convicted felon.

See also

References

  • Chriss, Chuck. (2002). Body armor development after WWII. Retrieved February 7, 2005, from [1] (http://www.olive-drab.com/od_soldiers_gear_body_armor_korea.php)
  • Chriss, Chuck. (2005). U.S. body armor (flak jackets) in WWII. Retrieved February 7, 2005, from [2] (http://www.olive-drab.com/od_soldiers_gear_body_armor_wwii.php)
  • Military. (2004). Isaac Newton and the assault rifle: Body armor innovations. Retrieved February 7, 2005, from [3] (http://www.military.com/soldiertech/0,14632,Soldiertech_Armor,,00.html)

External links

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