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Bullet-Proof Sheets of Carbon Nanotubes
An anonymous reader notes a CNN.com report on Nanocomp Technologies, the first in the world to make sheets of carbon nanotubes. "In April, [CEO] Lashmore had a mechanical multicaliber gun shoot bullets at different versions of his sheet, each less than a fifth of an inch thick. ... Army tests show the material works as well as Kevlar. The military also hopes to replace copper wiring in planes and satellites with highly conductive nanotubes, saving millions of dollars in fuel costs."
Kevlar and carbon nano-tubes are not particularly dense. The ideal projectile material is extremely dense, its why lead and depleted uranium are often used instead (or in conjunction with) of hard brass or steel.
People also used leather as armor, but so far no one has dug up a leather sword. The physical properties of kevlar as used for armor are entirely different from the physical properties of a good bullet. Kevlar has very high tensile strength allowing it to spread the impact over a large area by deforming and pulling on all the threads around it. With a bullet, you want all the force located in one small, strong, pointy area for penetration; which is why armor penetrating rounds are jacketed or tipped in a metal much stronger than lead or copper(steel, tungsten, depleted uranium).
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All or most armor manufacturers use a table top mounted "test gun" that they can change out the barrel and receiver to fire different caliber to test the protective effectiveness of their product. I don't think anyone can buy one of these you have to get them specially built.
If you ever watch any History or Discovery channel show(s) about fire-arms chances are they show a few of these.
you want all the force located in one small, strong, pointy area for penetration; which is why armor penetrating rounds are jacketed or tipped in a metal much stronger than lead or copper(steel, tungsten, depleted uranium).
Actually, the advantage of DU isn't its strength but its density:
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A few years back, the trend in armor-piercing rounds was the teflon-coated brass round. They are now banned, though not for the Teflon coating (which wears off in the barrel or peels away in flight), but because of the hard cores.
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For clarification, Teflon coating of projectiles is designed to reduce barrel wear, and has nothing to do with penetration.
Most ammo manufacturers now use molybdenum coatings - not sure if that is because it is more effective, or because of the dumb "Teflon-coated cop-killing bullets that go through a bullet-proof vest!" bullshit the Brady group shrieked about in the 90s. FWIW, most any rifle bullet will penetrate light armor, and there are several surplus rounds that can even penetrate level IIIa from a pistol - 7.62x25 Tokarev being the most popular, in the CZ-52.
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Well its really both it's density and hardness. The Brinell hardness of U-238 is 2,400, which is just shy of tungsten at 2,570. Iron is 490.
Also, DU has incendiary properties (somewhat similar to magnesium) which make it great as an artillery shell.
Working raw titanium can be a pain. If you aren't careful, it will gall and go all lumpy.
It'll catch fire before it melts, unless it is in an inert gas environment. Far right on the periodic table inert, it'll burn in nitrogen.
On the plus side, you'll have lots of titanium oxide dust around. If you think FeO+Al is fun, try TiO+Al+Fluorite+Calcium Sulfate. It won't just burn through an engine block, it might keep going into the concrete @ 3800 F
The definition of AP ammo is at 18 USC sec. 921(a)(17): "(B) The term `armor piercing ammunition' means- (i) a projectile or projectile core which may be used in a handgun and which is constructed entirely (excluding the presence of traces of other substances) from one or a combination of tungsten alloys, steel, iron, brass, bronze, beryllium copper, or depleted uranium; or
(ii) a full jacketed projectile larger than .22 caliber designed and intended for use in a handgun and whose jacket has a weight of more than 25 percent of the total weight of the projectile.
It's important to note that this subsection relates ONLY to ammunition which can be loaded in handguns. There are few shops with CNC lathes which turn out solid brass bullets, supposedly of highly uniform density metal, which are sold to be hand loaded for long range shooters. Steel and tungsten core rifle ammo is commonly available--or at least it was before all the hoarding hullabaloo.
This is the reason why FN Herstal couldn't ship the 5.7x27mm cartridge with the SS190 Steel/Aluminum core bullet. It can be used both in their PS90 carbine and FiveSeven pistol. If they only marketed the carbine in the US, an argument could be made that they would be legally able to ship the SS190 ammo, as it isn't intended for handguns, and by definition isn't armor piercing ammo, per federal law.
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