Bulletproof vest

From Free net encyclopedia

Image:Bodyarmor.jpg A bullet-resistant vest (body armor) - is an article of protective clothing that works as a form of armour to minimize injury from projectiles fired from handguns, shotguns and rifles . They are commonly worn by police forces, the military, and private security and civilians where legal. However, they are sometimes worn extralegally, by those that the relevant government refuses to allow body armor.

The term "bulletproof" is a misnomer since these vests (depending on their armor level, see below) may provide little or no protection against rifle ammunition or even against handgun ammunition fired from a pistol-caliber carbine. The exception is the common .22 LR ammunition, which can usually be stopped by these vests even when fired from a rifle. These vests are usually protective against handgun ammunition fired from handguns (once again, depending on their armor level.)

However, 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 handgun bullets and some rifles, if the bullet actually hits the plate. These types of vests have become standard in military use, as Kevlar-only vests are ineffective against most military rifle rounds. The CRISAT NATO standard for body armour specifies the use of titanium backing.

A vest does not protect the wearer by deflecting bullets. Instead, the layers of material catch the bullet and spread its force over a larger portion of the body, absorbing energy more quickly and hopefully bringing it to a stop before it can penetrate into the body. This tends to deform the bullet, further reducing its ability to penetrate. While a vest can prevent bullet wounds, the wearer still absorbs the bullet's energy, which can cause blunt force trauma. The majority of users experience only bruising, but impacts can cause severe internal injuries. This is considered to be unimportant by many, as it seems guaranteed any bullets or shrapnel with sufficient force to cause notable injuries would do more damage without the vest. Most vests offer little protection against arrows, ice picks, or stabbing knife blows. As the force is concentrated in a relatively small area with such bladed weapons, the tip of the object can push through the weave of most bullet-resistant fabrics. Specially-designed vests are available that can provide protection against bladed weapons, and sharp objects; they are often used in prison-guard vests. This is done by coating the outer surface of the vest with tiny crystals of a sandpaper-like material or placing 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.

1 History
2 Performance standards
3 The future of bulletproof vests
4 Legality
5 See also
6 References
7 External links

[edit]

History

Firearms made their entry at the end of the medieval era. When many knights and nobles purchased their new breast plates, they wanted “proof” that the armor would protect them from early bullets. Armor makers would shoot the breast plates, and the resulting dent in the new armor was provided as evidence that it was “bullet-proofed”.

The oldest bullet-resistant fabric vests were made from silk. At the forefront, the Rev. Casimir Zeglen of Chicago, IL developed a bullet proof vest made of silk fabric at the end of the 19th century. These expensive vests (often costing US $800 each in 1914, equal to $15,000 in 2005) were capable of stopping relatively slow rounds from black powder handguns. 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 World War I, the United States developed several types of body armor, including the chrome nickel steel Brewster Body Shield, which consisted of a breastplate and a headpiece and could withstand Lewis Gun bullets at 2,700 ft/s (820 m/s), but it was clumsy and heavy at 40 pounds (18 kg). Another type of body armor was designed in February 1918 by the Metropolitan Museum of Art. This breastplate was based on certain armor of the 15th century, weighed 27 pounds (12 kg), and was considered to be very noisy and restricting of the movements of the wearer. A scaled waistcoat of overlapping steel scales fixed to a leather lining was also designed; this armor weighed 11 pounds (5 kg), fit close to the body, and was considered comfortable.

During the late 1920s through the early 1930s, criminals in the United States 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 of up to approximately 1000 ft/s (300 m/s). This led to the development of the .357 Magnum cartridge for the use of law enforcement agents such as the FBI to overcome these vests.

In the early stages of World War II, some work was performed in the United States on designing body armor for infantrymen, but most models were too heavy, incompatible with existing equipment, and restricted the mobility of the wearer. For these reasons, development of infantry body armor was discontinued and attention was diverted to the development of "flak jackets" for aircraft crews. These flak jackets were made of nylon fabric and only capable of stopping flak and shrapnel, not the .38 Special or .357 Magnum bullets. The Japanese produced a few types of infantry body armor during World War II, but they did not see much use. Near the middle of 1944, development of infantry body armor in the United States restarted. Several vests were produced for the US military, including but not limited to the T34, the T39, the T62E1, and the M12.

Image:Sn-42b.jpg There were several models of body armor in the Red Army, called SN-38, SN-39, SN-40, SN-40A, and SN-42. The number denotes the design year. All were combat tested, but only the SN-42 (in Russian language "Stalynoi Nagrudnik" SN=steel vest or CH-42) was put in production. It consisted of two pressed steel plates that protected the front torso and groin. The plates were 2mm and weighed 3.5kg. This armor was supplied to SHISBr (assault engineers) and Tankodesantnikam (infantry that rode on tanks) of some tank brigades. Real combat experience showed that the MP-40 9mm bullet failed to penetrate at around 100-125m. It was very useful in dense, intense urban battles (Stalingrad) where the Germans used the MP-40 predominantly, but, because of its weight, was not practical for soldiers charging across an open field.

During the Korean War several new vests were produced for the United States military, including 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 the Ranger Body Armor was developed, which again was an improvement over the previous armor but still had its flaws: "it was heavier than the anti-fragment armor already worn by the infantry and offered less protection" (Military, 2004).

The newest armor issued by the United States military is known as Interceptor Multi-Threat Body Armor System. While it has its flaws, it protects the wearer from most low- to mid-velocity threats. Modern bullet-resistant vests made from woven Kevlar were tested by United States police forces in 1975. Since then several new fibers and construction methods for bulletproof fabric have been developed besides woven Kevlar, such as DSM's Dyneema, Akzo's Twaron, Toyobo's Zylon (now controversial, as new studies report that it degrades rapidly, leaving wearers with significantly less protection than expected), or Honeywell's GoldFlex. These newer materials are advertised as being lighter, thinner and more resistant than Kevlar, although they are much more expensive.

[edit]

Performance standards

Both the Underwriters Laboratories (UL Standard 752) and the United States National Institute of Justice (NIJ Standard 0101.04) have specific performance standards for bullet resistant vests used by law enforcement. The US NIJ rates vests on the following scale against penetration and also blunt trauma protection (deformation) (Table from NIJ Standard 0101.04):

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 maximum 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 maximum 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 maximum 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 maximum 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 maximum 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 maximum 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 maximum 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 maximum 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 maximum 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 maximum 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.

An Aramid 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; it may also weaken the structure of the fiber by breaking hydrogen bonds, see Kevlar for details). Most bulletproof vests have panels in sealed enclosures, but waterproofing is usually not perfect. Dyneema based vests do not have the same difficulties with water.

[edit]

The future of bulletproof vests

In recent years advances in material science have opened the door to the old idea of an actual "Bulletproof vest" that will be able to stop handgun and rifle bullets without the assistance of heavy and cumbersome extra metal or ceramic plating. Researchers in the U.S.[1] and separately in the Hebrew University [2] are on their way to create artificial spider silk that will be super strong, yet light and flexible. Other research has been done to harness nano-technology to help create super strong materials that could be used in future bulletproof vest. In 2005 an Israeli company claimed [3] it was able to develop a nanomaterial based on Tungsten Disulfide that was able to withstand shocks generated by a steel projectile traveling at velocities of up to 1.5 km/second. The material was also reportedly subjected to a shock pressures generated by the impacts of up to 250 tons per square centimeter. During the test the material proved to be so strong that after the impact the samples remained essentially identical compared to the original material. Spider silk bulletproof vests and nano based armor are, as of early 2006, still in the future.

[edit]

Legality

United States Law 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.

Curiously enough, bulletproof vests remain legal in many countries where firearms are heavily restricted, such as the UK. One exception is Australia, where body armor has been prohibited for some time. This ban may have its origins in the late 19th century, when the iconic Australian outlaw and folk hero Ned Kelly used home-made armor with mixed results. While the steel armor worn by Kelly defeated the soft lead, low velocity bullets fired by police Martini-Henry rifles, it greatly restricted his movement.

[edit]

References

Chriss, Chuck. (2002). Body armor development after WWII. Retrieved February 7, 2005, from [4]
Chriss, Chuck. (2005). U.S. body armor (flak jackets) in WWII. Retrieved February 7, 2005, from [5]
Military. (2004). Isaac Newton and the assault rifle: Body armor innovations. Retrieved February 7, 2005, from [6]

[edit]