Why do Teflon coated rounds penetrate Teflon bullet-proof vests?

Question

Is the same true for kevlar?

Answer 1

http://www.nationalreview.com/kopel/kopel200403010926.asp

TEFLON BULLETS?
"Cop-killer" bullets are sometimes called "Teflon bullets," but this name reflects a serious misunderstanding. For example, in the movie Lethal Weapon 3, a so-called "Teflon bullet" from a medium-power handgun was supposedly able to penetrate several inches of hardened steel on a bulldozer blade. In the real world, however, no bullet could possibly perform such a stunt.

Actually, a Teflon coating is applied to the outside of a wide variety of ordinary ammunition. Teflon reduces the lead abrasion caused by the bullet's movement down the barrel of the gun. Thus, the barrel is kept cleaner, and is protected from excessive wear. Also, reduced abrasion means that fewer tiny lead air particles are produced, so the air is cleaner — an especially important consideration at indoor shooting ranges.

In addition, a Teflon coating on a bullet also makes the bullet safer to use in a self-defense context. The Teflon helps the bullet "grab" a hard surface such as glass or metal, and thus significantly reduces the risk of a dangerous ricochet. Similarly, canes or walking sticks are often coated with Teflon, so that they will not slip on hard, smooth surfaces.

So in order to reduce ricochets, KTW bullets as well as many ordinary types of defensive ammunition use Teflon or similar substances.

BODY ARMOR
As police officers know, the vests that they wear are "bullet-resistant," not "bullet-proof." The Bureau of Alcohol, Tobacco, Firearms and Explosives explains that "armor protection is rated in accordance with a specific threat. There is no such thing as 'bullet-proof' armor."

Manufactured from Kevlar (a synthetic fiber that is five times stronger than steel), body armor comes in a variety of grades. The higher the grade, the bulkier and less comfortable the armor is to wear, but the more ammunition it can stop. The highest grades of armor are often called "tactical armor" or "hard armor," and may contain steel or titanium.

At the top of the scale is Threat Level IV armor, which can stop even a high-powered rifle bullet. It takes a very strong vest to stop a big-game hunting-rifle bullet: The bullet travels at a high velocity, due to the long length of the rifle barrel; and has a large mass, since a hunting-rifle bullet must be large enough to bring down a moose, elk, or other large mammal.

Almost the only people who wear hard armor are SWAT team members on high-risk missions. Far more common for ordinary police use is "soft" body armor, made from Kevlar, and rated at Threat Levels IIA through IIIA. Level IIA armor can stop most handgun ammunition, while Level IIIA can stop almost any handgun bullet. Handgun ammunition is much easier to stop than rifle ammunition, since the handgun barrel is much shorter (less velocity) and handgun bullets are smaller (less mass).

Answer 2

Teflon Coated Bullets

Answer 3

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RE:
Why do Teflon coated rounds penetrate Teflon bullet-proof vests?
Is the same true for kevlar?

Answer 4

The original claim of Teflon was/is "It's like sliding wet ice on wet ice." Very low friction properties could conceivably lead to an "aid" to initial barrier penetration by something else with the same properties. But I'm no scientist. Why are they coating body armor with Teflon? Just to charge a lot more for the armor?
Military bullets have hard pointed bullets but not sharp tips. The recent progress in other world ammo technology is trying out ammo that is smaller, lighter, and higher velocity with fairly sharp tips made to defeat most body armor. Wonder what they know that we don't know?
No. Kevlar is used more as thread and tightly woven Kevlar cloth is used for ballistic armor, usually backed up with padding and sometimes slim metal plates. Most common ammo won't get much, if any, past the Kevlar. Not sure if Kevlar helmets use the cloth or is pressure molded as a semi-liquid or is layers of Kevlar cloth/Fiberglas pressed into shape.

Answer 5

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The only 9mm rounds with "high penetration" are the hot sub-machine rounds made in Eastern Europe. The standard 9mm round here is a light-weight. Used to be the KTW was the best-known AP handgun round. If you're seriously considering body armor, a few things to consider: They aren't comfortable, especially in the summer. If you wear one, make sure it's concealed. The top of the carrier has a nasty habit of peeking over the top of button-up shirts. That is the quickest way to catch a bullet between the eyes. If you wear a vest, make sure you put the trauma plate in, too. Might just keep your heart beating if you take a round in the chest. And higher level vests weigh more and are stiffer. Used to be, anyway. It's been a few years since I've worn one.

Answer 6

Bulletprrof vest are made of kevlar. Teflon had nothing to do with whether a bullet will penetrate a vest. Things that does matter are metal composition of the bullet, shape of the bullet, velocity of the round fired, and the level of protection of the vest in question.