Bulletproof vest

Man in body armor

A ballistic vest, otherwise known as a bullet-proof vest or body armor, is a protective torso covering that absorbs the impact from gun-fired projectiles and explosive fragments. Soft vests made from layers of tightly-woven fibres protect wearers from projectiles fired from handguns, shotguns, and shrapnel from explosives such as hand grenades. When metal or ceramic plates are used with a soft vest, it can also protect wearers from shots fired from rifles. Soft vests are commonly worn by police forces and private security guards, and hard-plate reinforced vests are worn by combat soldiers in the armies of various nations as well as armed response police forces.

Overview

The term "bullet-proof" is a misnomer since these vests, depending on the 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, depending on the armor level of the vest.

Vests may be augmented with metal (steel or titanium), ceramic or polyethylene plates that provide extra protection to vital areas. These hard armor plates have proven effective against all handgun bullets and a range of rifles. These "tactical body armor" vests have become standard in military use, as soft body armor vests are ineffective against most military rifle rounds. The CRISAT NATO (Collaborative Research Into Small Arms Technology-North Atlantic Treaty Organization) standard for body armor specifies the use of titanium backing. This titanium plate may be removable or sewn in.

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 still cause severe internal injuries.

Most vests offer little protection against arrows, ice picks, stabbing knife blows, bullets with their points sharpened or armor-piercing rounds. As the force is concentrated in a relatively small area with bladed weapons and armor-piercing rounds, they can push through the weave of most bullet-resistant fabrics. Specially-designed vests which protect against bladed weapons and sharp objects are often used in vests for prison guards and other law enforcement officers. Some materials like Dyneema offer considerable protection against bladed weapons and slash attacks.

History

Silk vests

The oldest bullet-resistant fabric vests were made from silk and they resembled medieval padded jacks, which used 18 to 30 layers of cloth to protect wearers from arrow penetration. In 1881 Dr. George Emery Goodfellow of Arizona witnessed a gunfight between two people. When he examined one man who had been shot through his breast pocket, he found that the bullet had been slowed by the layers of the man's silk handkerchief. Dr. Goodfellow documented various other cases of silk fabric protecting people from gunshot wounds, including a noted case where a man's bandanna saved his carotid artery from being severed.

Casimir Zeglen of Chicago, Illinois used Goodfellow's findings to develop a bulletproof vest made of silk fabric at the end of the 1800s. Zeglen's expensive vests could stop the relatively slow rounds from black powder handguns. The vests cost $800 USD each in 1914, which is equivalent to about $15,000 in 2005 dollars. On June 28, 1914, Franz Ferdinand, Archduke of Austria, heir to the Austro-Hungarian throne was wearing a silk bulletproof vest. However, the vest did not protect him, because he was shot in the neck above the vest with a .32 ACP bullet fired by Gavrilo Princip using a handgun.

Steel breastplates

World War I German Infantrie-Panzer, 1918

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 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 armor of the 1400s, weighed 27 pounds (12 kg), and was considered too noisy and restricting. 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 more comfortable.

Padded vests

During the late 1920s through the early 1930s, gunmen from criminal gangs in the United States began wearing less-expensive vests made from thick layers of cotton padding and cloth. These early vests could absorb the impact of handgun rounds 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). To overcome these vests, law enforcement agents such as the FBI developed a more powerful type of handgun cartridge called the .357 Magnum cartridge.

World War II

In the early stages of World War II, the United States designed body armor for infantrymen, but most models were too heavy and mobility-restricting. As well, these armor vests were often incompatible with existing equipment. The military diverted its research efforts to developing "flak jackets" for aircraft crews. These flak jackets were made of nylon fabric and capable of stopping flak and shrapnel, but not bullets.

The Japanese army 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.

File:Sn-42b.jpg

Sn-42 Body Armor

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, "Stalynoi Nagrudnik", which is shortened to SN, meaning a steel vest or СН-42) was put in production. It consisted of two pressed steel plates that protected the front torso and groin. The plates were 2 mm and weighed 3.5 kg. This armor was supplied to SHISBr (assault engineers) and to Tankodesantniki (infantry that rode on tanks) of some tank brigades. The SN armor protected wearers from the German MP-40 9 mm bullet at around 100-125 meters, which made it useful in urban battles (Stalingrad). However, the SN's weight made it impractical for infantry soldiers on foot in an open outdoor setting, and the 7.92x57mm cartridges fired by the Mauser Karabiner 98k and MG42 easily penetrated it.

1960s-1970s

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). The Vietnam war era vests were simply various combinations of the nylon, new ceramics capable of stopping rifle rounds, fiberglass and steel armor raw materials used within WWII and Korean war military armor designs.

In 1968, American Body Armor was founded and produced a patented combination of quilted nylon faced with multiple steel plates. This armor configuration was marketed to American law enforcement agencies by the Smith & Wesson gun company under the trade name "Barrier Vest". The "Barrier Vest" was the first police vest to gain wide use during high threat police operations.

In the mid-1970s, the DuPont Corporation introduced Kevlar synthetic fiber, when woven into a fabric and layered, immediately was incorporated into a National Institute of Justice (NIJ) evaluation program to provide lightweight, concealable body armor to a test pool of American law enforcement officers to ascertain if everyday concealable wearing was possible. Lester Shubin, a program manager at the NIJ, managed this law enforcement feasibility study within a few selected large police agencies, and quickly determined that Kevlar body armor could be comfortably worn by police daily, and would save lives.

In 1975 Richard A. Armellino, the founder of American Body Armor marketed an all Kevlar vest called the K-15, comprised of 15 layers of Kevlar that also included a 5" X 8" ballistic steel "Shok Plate" positioned vertically over the heart and was issued U.S Patent #3,971,072 for this ballistic vest innovation. Similarly sized and positioned "trauma plates" are still used today on the front ballistic panels of most concealable vests, reducing blunt trauma and increasing ballistic protection in the center-mass heart/sternum area.

In 1976, Richard Davis, founder of Second Chance Body Armor designed this company's first all-Kevlar vest, named the Model Y. The lightweight, concealable vest industry was launched and a new form of daily protection for the modern police officer was quickly adapted. By the mid to late 1980s, an estimated 1/3 to 1/2 of police patrol officers wore concealable vests daily. By the year 2006, more than 2,000 documented police vest "saves" were recorded, validating the success and efficiency of lightweight concealable body armor as a standard piece of everyday police equipment.

1990s-2000s

Kevlar soft armor had its shortcomings because if "large fragments or high velocity bullets hit the vest, the energy could cause life-threatening, blunt trauma injuries" in selected, vital areas (Military, 2004). So the Ranger Body Armor was developed for the American military in 1994. Although it was the second modern US body armor that was able to stop rifle caliber rounds and still be light enough to be worn by infantry soldiers in the field, it still had its flaws: "it was still heavier than the concurrently issued PASGT (Personal Armor System for Ground Troops) anti-fragmentation armor worn by regular infantry and ... did not have the same degree of ballistic protection around the neck and shoulders" (Military, 2004).

The newer armor issued by the United States military to large numbers of troops is known as Interceptor Multi-Threat Body Armor System. The Kevlar Interceptor vest is intended mainly to provide shrapnel protection, but is rated for threats up to and including 9mm submachine gun fire. Small Arms Protective Insert (SAPI) plates, made of ceramic materials, are worn front and back and protect the vital organs from threats up to and including 7.62x51mm NATO rifle rounds.

Since the 1970s, several new fibers and construction methods for bulletproof fabric have been developed besides woven Kevlar, such as DSM's Dyneema, Honeywell's GoldFlex and Spectra, Teijin Twaron's Twaron, and Toyobo's Zylon (now controversial, as new studies report that it degrades rapidly, leaving wearers with significantly less protection than expected). These newer materials 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) 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) at a reference velocity of 329 m/s (1080 ft/s ± 30 ft/s) and .380 ACP Full Metal Jacketed Round Nose (FMJ RN) bullets, with nominal masses of 6.2 g (95 gr) at a reference velocity of 322 m/s (1055 ft/s ± 30 ft/s).
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) at a reference velocity of 341 m/s (1120 ft/s ± 30 ft/s) and .40 S&W caliber Full Metal Jacketed (FMJ) bullets, with nominal masses of 11.7 g (180 gr) at a reference velocity of 322 m/s (1055 ft/s ± 30 ft/s). 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) at a reference velocity of 367 m/s (1205 ft/s ± 30 ft/s) and 357 Magnum Jacketed Soft Point (JSP) bullets, with nominal masses of 10.2 g (158 gr) at a reference velocity of 436 m/s (1430 ft/s ± 30 ft/s). 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) at a reference velocity of 436 m/s (1430 ft/s ± 30 ft/s) and .44 Magnum Semi Jacketed Hollow Point (SJHP) bullets, with nominal masses of 15.6 g (240 gr) at a reference velocity of 436 m/s (1430 ft/s ± 30 ft/s). 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) at a reference velocity of 847 m/s (2780 ft/s ± 30 ft/s) or less. 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) at a reference velocity of 878 m/s (2880 ft/s ± 30 ft/s). 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 armor 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 and Spectra based vests do not have the same difficulties with water.

The future of bulletproof vests

In recent years advances in material science have opened the door to the old idea of a literal "bulletproof vest" that will be able to stop handgun and rifle bullets without the assistance of heavy and cumbersome extra metal or ceramic plating. Current soft body armor can stop most handgun rounds. Plates are currently needed to stop rifle rounds and unique handgun rounds such as 7.62x25. Research aims to develop artificial spider silk which could be super strong, yet light and flexible. Other research has been done to harness nanotechnology to help create super strong materials that could be used in future bulletproof vests.

Currently, there are two methods by which nanomaterials are being implemented into body armor production. The first is based on nanoparticles within the suit that become rigid enough to protect the wearer as soon as a pressure threshold is surpassed, which the impact of a bullet would register. These nano-infused suits are significantly lighter than alternative forms of body armor because of the properties that govern them.

The second was introduced in 2005 by American company ApNano. They developed a material that was always rigid, and announced[1] that this nanocomposite based on Tungsten Disulfide 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 able to withstand shock pressures generated by the impacts of up to 250 tons per square centimeter. During the tests, the material proved to be so strong that after the impact the samples remained essentially unmarred. Additionally, a recent study in France tested the material under isostatic pressure and found it to be stable up to at least 350 tons/cm². As of mid-2006, spider silk bulletproof vests and nano-based armors are being developed for potential market release.

Legality

Body armor is legal in most countries. 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.

United States law restricts possession of body armor for convicted violent felons. Many US states also have penalties for possession or use of body armor by 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. In other states, such as Kentucky, they do not prohibit possession, but deny probation or parole for a person convicted of certain violent crimes while wearing body armor and carrying a deadly weapon.

Canadian legislation makes it legal to wear and to purchase body armor such as ballistic vests. However, there are current proposals to the legislation to make it illegal to wear such body armor during the commission of a criminal offense.

In Germany, body armor is are illegal because they are classified as a passive weapon.

External links

• How Stuff Works - Body Armor