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.
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.
Bulletproof vest are rated to certain standards of protection depending on what they can stop. Here is some info on the ratings from Wikipedia.
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.
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.
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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A cite for ya RandomLetters. From Here 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]
Really? Then why would military men wear them?
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.
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.
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.
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.
Great article on this on howstuffworks:
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?
Ok, the ceramics question was answered in the how stuff works webpage. Thanks for that link.
They either work quite well, or else not at all. There really doesn’t seem to be any middle ground.