# how does a bullet-proof jacket work?
**URL:** https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762
**Category:** Factual Questions
**Created:** [September 2, 2004, 1:44pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762 "2004-09-02T13:44:40Z")
**Posts on this page:** 17
**Page:** 1
### Author:  [@drhess](https://boards.straightdope.com/u/drhess)
#### Post date: [September 2, 2004, 1:44pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/1 "2004-09-02T13:44:40Z")
How does body armor against bullets/fragments work? What are they made of and what can they stop? I guess the velocity, angle and kind of ballistic or fragment that comes at you makes a big difference, of course, but what’s the “most” they can stop? I assume there’s lots of testing done on this and some is public. But, I’m also just wondering how something “light” enough to wear (weight?) stops a bullet.
(Also, do soldiers just wear a vest? Why not legs and neck, etc. too?)
Thanks.
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### Author:  [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)
#### Post date: [September 2, 2004, 1:53pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/2 "2004-09-02T13:53:18Z")
They spread the force of the impact out over a bigger area so that the pressure (force per unit area) on the body is lowered and the bullet doesn’t penetrate. I believe Kevlar is the material used these days.
Police tried to get teflon tipped bullets outlawed because the tend to penetrate the vest.
Only vital areas are covered. It’s a compromise between protection and being able to act effectively. The protectors are a little bulky and would restrict movement a lot if everything were covered. Wounds to arms and legs aren’t necessarily fatal although they are damned inconvenient. Helmets are worn in some cases and the face and neck are small targets and hard to hit.
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### Author:  [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)
#### Post date: [September 2, 2004, 1:56pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/3 "2004-09-02T13:56:04Z")
A site about [Kevlar.](http://www.lbl.gov/MicroWorlds/Kevlar/)
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### Author:  [@silenus](https://boards.straightdope.com/u/silenus)
#### Post date: [September 2, 2004, 2:03pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/4 "2004-09-02T14:03:16Z")
Another [site](http://www.secondchance.com/home.asp) on body armor.
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### Author:  [@RandomLetters](https://boards.straightdope.com/u/RandomLetters)
#### Post date: [September 2, 2004, 5:38pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/5 "2004-09-02T17:38:22Z")
Bulletproof vest are rated to certain standards of protection depending on what they can stop. Here is some info on the ratings from [Wikipedia.](http://en.wikipedia.org/wiki/Bullet_proof_vest)
> [@](#):
>
> ```
> * I - minimal protection from small-caliber bullets
> * II - can be worn under a T-shirt
> * IIA -typically worn by police in low-risk situations and by security guards
> * III - bulky, usually only worn in high-risk situations by SWAT teams; ceramic or metal plate insert required to achieve this level of protection
> * IIIA - heaviest that can be worn under normal clothing, commonly used by police
> * IV - bulky, usually only worn in high-risk situations by SWAT teams; ceramic or metal plate insert required to achieve this level of protection, which is higher than even III
> * V - (also known as a bomb suit) extremely cumbersome and bulky; used by bomb squad personnel
>
> ```
Bullet resistant vest are typically made of Kevlar, though for protection against rifle rounds steel or ceramic trama plates are added to protect certain chest regions.
> [@David Simmons](#):
>
> Police tried to get teflon tipped bullets outlawed because the tend to penetrate the vest.
Note that teflon in and of itself does nothing to aid a bullet in penetrating armor. It is just that armor piecing rounds tend to be made of hard materials (hard steel or tungsten, for example) that would scratch the barrel, so they are coated with teflon to prevent abrasion. Non-armor piecing bullets are sometimes also coated in teflon, for the same reasons.
Further more, the whole “cop-killer” hangun bullet scare is a myth, created by a 1982 NBC TV special.
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### Author:  [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)
#### Post date: [September 2, 2004, 6:08pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/6 "2004-09-02T18:08:03Z")
It should be added that body armor is primary useful against _handgun_ rounds. I’ve read that most _rifle_ rounds – even a .22LR – can penetrate most type I through type III vests.
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### Author:  [@BF](https://boards.straightdope.com/u/BF)
#### Post date: [September 2, 2004, 8:14pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/7 "2004-09-02T20:14:11Z")
[slight hijack]
> [@RandomLetters](#):
>
> Further more, the whole “cop-killer” hangun bullet scare is a myth, created by a 1982 NBC TV special.
A cite for ya **RandomLetters**. [From Here](http://www.guncite.com/gun_control_gcgvcopk.html) Note: Pro-gun site.
"In the mid 1960’s, Dr. Paul Kopsch (an Ohio coroner), Daniel Turcos (a police sergeant) and Donald Ward (Dr. Kopsch’s special investigator) began experimenting with special purpose handgun ammunition. Their objective was to develop a **law enforcement round** capable of improved penetration against hard targets like windshield glass and automobile doors. Conventional bullets, made primarily from lead, are often ineffective against hard targets especially when fired at handgun velocities. In the 1970’s, Kopsch, Turcos and Ward produced their “KTW” handgun ammunition using steel cored bullets capable of great penetration. Following further experimentation, in 1981 they began producing bullets constructed primarily of brass. The hard brass bullets caused exceptional wear on handgun barrels, a problem combated by coating the bullets with Teflon. The Teflon coating did nothing to improve penetration, it simply reduced damage to the gun barrel.
Despite the facts that “KTW” ammunition had **never been available** to the general public and that no police officer has ever been killed by a handgun bullet penetrating their body armor, the media incorrectly reported that the Teflon coated bullets were designed to defeat the body armor that law enforcement officers were beginning to use. The myth of “Cop-killer” bullets was born." [emphasis mine]
[/slight hijack]
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### Author:  [@aegypt](https://boards.straightdope.com/u/aegypt)
#### Post date: [September 2, 2004, 8:43pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/8 "2004-09-02T20:43:09Z")
> [@Crafter\_Man](#):
>
> It should be added that body armor is primary useful against _handgun_ rounds. I’ve read that most _rifle_ rounds – even a .22LR – can penetrate most type I through type III vests.
Really? Then why would military men wear them?
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### Author:  [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)
#### Post date: [September 2, 2004, 9:10pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/9 "2004-09-02T21:10:25Z")
> [@BF](#):
>
> [slight hijack]
>
> A cite for ya **RandomLetters**. [From Here](http://www.guncite.com/gun_control_gcgvcopk.html) Note: Pro-gun site.
>
> "In the mid 1960’s, Dr. Paul Kopsch (an Ohio coroner), Daniel Turcos (a police sergeant) and Donald Ward (Dr. Kopsch’s special investigator) began experimenting with special purpose handgun ammunition. Their objective was to develop a **law enforcement round** capable of improved penetration against hard targets like windshield glass and automobile doors. Conventional bullets, made primarily from lead, are often ineffective against hard targets especially when fired at handgun velocities. In the 1970’s, Kopsch, Turcos and Ward produced their “KTW” handgun ammunition using steel cored bullets capable of great penetration. Following further experimentation, in 1981 they began producing bullets constructed primarily of brass. The hard brass bullets caused exceptional wear on handgun barrels, a problem combated by coating the bullets with Teflon. The Teflon coating did nothing to improve penetration, it simply reduced damage to the gun barrel.
>
> Despite the facts that “KTW” ammunition had **never been available** to the general public and that no police officer has ever been killed by a handgun bullet penetrating their body armor, the media incorrectly reported that the Teflon coated bullets were designed to defeat the body armor that law enforcement officers were beginning to use. The myth of “Cop-killer” bullets was born." [emphasis mine]
>
> [/slight hijack]
Thanks to you and **RandomLetters** I can stop passing our bum dope on teflon coated bullets. After you brought it to the surface I now remember reading that the teflon did not in fact result in better penetration but I have a propensity for remembering the wrong things. Like remembering things from 60 years ago clearly but forgetting were I put my pencil this morning.
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### Author:  [@silenus](https://boards.straightdope.com/u/silenus)
#### Post date: [September 2, 2004, 10:01pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/10 "2004-09-02T22:01:37Z")
> [@aegypt](#):
>
> Really? Then why would military men wear them?
They wear them to primarily protect against shrapnel and shell splinters. That is why they are called “flak jackets.”
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### Author:  [@Alessan](https://boards.straightdope.com/u/Alessan)
#### Post date: [September 2, 2004, 10:39pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/11 "2004-09-02T22:39:39Z")
> [@silenus](#):
>
> They wear them to primarily protect against shrapnel and shell splinters. That is why they are called “flak jackets.”
Also, the more modern military vests contain ceramic plates that have a very good chance of stopping rifle ammunition, at least up to the M-16/Kalashnikov range. the pales only cover the vital regions, though.
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### Author:  [@Jman](https://boards.straightdope.com/u/Jman)
#### Post date: [September 2, 2004, 10:52pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/12 "2004-09-02T22:52:40Z")
Just to add to what Alessan said: The interceptor body armor (what we wear in combat nowadays) has multi-ply Kevlar sheeting throughout, which is good enough to stop grenade frag, shrapnel, and bullets up to 9mm. It can also stand an OK chance of stopping 7.62mm rifle rounds, providing that they’ve hit somthing relatively solid beforehand (so, they offer SOME protection inside a vehicle if the bullet has torn up some metal before getting to the vest). However, they won’t stop a rifle round from any normal range, if you are shot cleanly. The ceramic plates (which are thick and heavy) will stop 7.62 rifle rounds.
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### Author:  [@Jman](https://boards.straightdope.com/u/Jman)
#### Post date: [September 2, 2004, 10:56pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/13 "2004-09-02T22:56:06Z")
Just to add to what Alessan said: The interceptor body armor (what we wear in combat nowadays) has multi-ply Kevlar sheeting throughout, which is good enough to stop grenade frag, shrapnel, and bullets up to 9mm. It can also stand an OK chance of stopping 7.62mm rifle rounds, providing that they’ve hit somthing relatively solid beforehand (so, they offer SOME protection inside a vehicle if the bullet has torn up some metal before getting to the vest). However, they won’t stop a rifle round from any normal range, if you are shot cleanly. The ceramic plates (which are thick and heavy) will stop 7.62 rifle rounds.
Sorry if this double posts - I had a 3 minute time out with no action.
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### Author:  [@FlippyFly](https://boards.straightdope.com/u/FlippyFly)
#### Post date: [September 2, 2004, 10:58pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/14 "2004-09-02T22:58:25Z")
Great article on this on howstuffworks:
> **[How Body Armor Works](https://science.howstuffworks.com/body-armor.htm)**
>
> Body armor is essential for many people in high-risk professions. The strange thing is, the most common armor is actually a high-tech, soft netting. Learn how modern armor technologies stop bullets.
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### Author:  [@drhess](https://boards.straightdope.com/u/drhess)
#### Post date: [September 3, 2004, 2:45pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/15 "2004-09-03T14:45:01Z")
Interesting stuff. So no police officer has been killed (how about injured) by a bullet passing through their vest? Or just it has happened but it wasn’t a “sepcial” bullet?
Also, ceramic? My idea of ceramic is plates in the kitchen. Seems brittle. Is that the idea? Why does that help?
Plus, it they can make bullet proof jackets, why not bullet proof vehicles?
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### Author:  [@drhess](https://boards.straightdope.com/u/drhess)
#### Post date: [September 3, 2004, 2:48pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/16 "2004-09-03T14:48:28Z")
Ok, the ceramics question was answered in the how stuff works webpage. Thanks for that link.
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### Author:  [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)
#### Post date: [September 3, 2004, 3:00pm UTC](https://boards.straightdope.com/t/how-does-a-bullet-proof-jacket-work/262762/17 "2004-09-03T15:00:26Z")
> [@](#):
>
> how does a bullet-proof jacket work?
They either work quite well, or else not at all. There really doesn’t seem to be any middle ground.