Stopping the bullet

[Jacks Complete]

Having searched around the forum, I have found not a lot on the subject of armour/armor.

There is a lot of stuff about on the 'net, but a lot of it is wrong, in as much as it contradicts it's self.

Any armour that we make is likely to be improvised, and, while not a weapon, this section is as close as it gets. Perhaps a "defensive aids" section would be a good idea?

So, how do you stop those .50 BMG rounds, or an APDFS anti-tank round? What kind of thickness and type of material do you need, and so on.

Culled from the forum, there are people who know various bits, as they have tested things.

I used to used a 3/8ths of an inch steel bar as my test, but gave up after putting a 7.62 through it. I dug back a foot, but still couldn't find the bullet. It was just a standard bit of copper 7.62 vs. mild steel.
The mess a solid slug made of it was funny, but the slug didn't penetrate (it was a brass one, for anyone familier with my other thread). If you had been wearing it as armour, you would have died as you wouldn't be able to breathe! The dent was two inches deep, and the back cracked.


For mobile armour, I think treadplate would be quite good, as it would space well from the tread (two bits tread to tread) and the inside could be filled with gravel. Also, the face is hardened (normally) and it is easily available compared to armour plate. It is expensive, but you get what you pay for!

Wire each plate to a heavy duty spark generator. That will stop shaped charge warheads, and the random nature of the gravel will protect against spalling from HESH charges. The outer plate should be something like 4.5mm and the inside should be as thick as possible, or multiple sheets. It needs to be thick enough that the gravel destroys itself rather than the inside plate. Also, the air gap will provide heat insulation, should you get napalmed or firebombed. Filling the gaps in the gravel with sand might be even better, but this is all theory!

On the inside of the inside plate, I would want something like fibreglass or carbon fibre or Kevlar matting, resined into place. This would stop rust from condensation, as well as spall, and allow that extra bit of protection.

If you want vision slots, go with thick polycarbonate slabs, held in really well, as you don't want them to pop through if hit!


Has anyone got any army manuals or anything, with thicknesses of earth, sand, concrete, etc. needed to stop various things?

From various manufacturers there is a statement that 12.5 mm of armour is enough to stop 7.62mm AP, as is 27mm of armoured glass. This is from point blank (presumeably used to refer to end of the muzzle, rather than correctly!) and with the best steel plate available. Presumeably the glass is layered polycarbonate and glass. (Source: Weapons and equipment of counter-terrorism, 1994)

Perhaps another thread should deal with bulletproof glass, etc.?

[vulture]

Forget steel. You need high tech material. Titanium, SiC or boronnitride. Lightweight and strong as hell. Titanium sheet metal with a SiC coating is going to seriously deform any round that hits it, because they're harder than any other material commonly used in bullets.

Anyways, I'd say you need to layers. One to take the punch out of the round, that is absorb the energy and another one to stop it from penetrating. Now, I haven't got a clue which one should come first.

[PHAID]

Just go basic and use several layers of 1/8" lexan, Its basicly what most "bullet proof glass" is made of.

The comercial layerd lexan can stop armor piercing .30 cal rounds and is around 1-2" thick.

I have tested rounds on various metals and found that they dont work well unless they are quite thick or at a sharp angle.

A .223 SS109 round will penetrate 4 1/2" Al plates and mild steel up to 1/2" ( it may do more but that is all i had to test on)

The standard .223 m855 round and the 7.62x39mm rounds will only produce large crators in the 1st Al plate.

[apathyboy]

Well, if you're talking about personal armor, the best so far is a 2 layer system
on the outside, you have a fairly thick layer of hard substance (I think the army uses some kind or ceramic, but a layer or 2 of windshield glass might work). This first layer fragments the round and tears up its jacket.
Then there's a layer of kevlar armor (lots of layers of kevlar cloth) bonded (epoxied?) to the back of the ceramic plate..
anyways the idea is that the hard surface fragments and tears up the round, and then the kevlar stops it just like it would a hollowpoint bullet.
This combination will apparently stop an AK round (7.62 x 39mm).

This is kind of limited because it brings back rigid armor and its heavier than regular soft body armor, so its mainly for the torso and maybe upper legs - places where it's very bad to be shot.

Short refresher on normal soft body armor: it doesnt actually stop the round, your body does. Punching a hole in kevlar cloth is hard, because punching a hole in tightly woven cloth means breaking a lot of strands, and kevlar has a lot of tensile strength. A blunt bullet i.e. hollowpoints can't penetrate, so its energy is spread out over a larger area, acting more like a beanbag round. Its the difference between being knifed and being hit with a baseball bat. The human body can take blunt trauma better than it can take things stabbed into it ;) .

However sharper, longer bullets don't have to break as many strands for their weight (energy) and so can get through it.

As far as APFSDS rounds go, well, got any depleted uranium or tungsten alloy lying around? You just need as hard and dense a metal as you can find, and lots of it.

[Ammonal]

Could a suggestion of the proposed weight of this body armour be made, because stopping armour penetrating rounds(the name says it all) would be a very hard problem to solve while maintaining the user not having to haul around 50kg of armour on his torso, legs, etc.
Wouldnt it be more feasilble to avoid having armour penetrating rounds fired at you?
Not being a smartarse or anything, I like the idea; but I would also like to be able to move and standup with the armour on.

[Jacks Complete]

I wasn't really talking about body armour and the like, but hey, whatever...

Apathyboy,

You are right about the soft nature of the Kevlar vests at the I and II level. They are designed for very low powered threats, though. Don't forget, a (sharp) knife will go right through soft Kevlar, as it just cuts a few strands, then you! IIA has some hard panels in it, in some designs, but are mostly soft.

Almost all of them have pockets for ceramic plates, so you can increase the level of protection.

Ammonal,

That's why they are banned most places! Obviously, you could make them with a bit of steel, though.

PHAID,

Sorry, what do you mean by "I have tested rounds on various metals and found that they dont work well unless they are quite thick or at a sharp angle."? Do you mean that most metals you have shot at have to be at a grazing angle to stop the bullet, or otherwise pretty thick, to stop the bullet?

If so, what sort of bullets (Lead, Lead with copper jacket, steel case, steel core, etc.) and what sorts of metals? It is no surprise that soft metals won't stop a bullet, not on thier own, at least.

Vulture,

I think you missed the point a bit. If we had two inch plates of Titanium and Kevlar backing lying about the place, we could sell them for silly money, and buy a house or two.

This is "Improvised weapons", not "Weapons I could make if I had ten years, millions of dollars, and no life", hence a suggested way to make a fairly good (in theory) armour from scrap and easy to find materials.

I want thicknesses of sand banks/bags, bricks, and concrete, earth, etc. as well as steel plates, as they are far easier to get hold of!

[PHAID]

Jack's Complete

What i ment by the thickness was for standard metal plates that anyone can easily get, not the armor that military uses.

As for the angle i ment that to defeat rounds with a thiner metal plate it needs to at an angle so that the round deflects rather than punch into the plate.

The rounds ive tested were the standard military issue full metal jacketed rounds with the exception of the .223 SS109 round as it has a tungsten penetrator.

I wasn't doing a serious test so i didnt record and photograph my tests.

Next time i go to the Range ill see if i can get downrange to get some examples of the damage that the rounds do, they normaly use cars for targets on the machinegun shoots so i can check out what several differant calibers do on the engine block.

The next sceduled big shoot is in april so i hope to get some good video, if you have a preferance for a particular weapon or caliber let me know and ill be sure to get the info you need.

[Jacks Complete]

You mean Knob Creek, or something of that ilk, don't you???

That is the coolest damned thing I have EVER seen, and that includes a private armoury and machinegun range I visited once. Sure, firing an MP5 is neat, handling a protype automatic pistol is cool, but watching those guys shoot automatics at cars and barrels... :D :D :D

Can you tell what I really like?

I so have to save up and go to one of those, before they get banned. Maybe ask Satan Claws, or someone.

Anyway, if you could find some info on 7.62/.308, .50, and .223/5.56 that would be cool, as they are the most common rounds you see about the place on mil. spec. stuff. 9mm and .40 might be handy as well.

I am amazed that the Tungsten 5.56 went through 4.5" of aluminium, though. What does one of those bullets weigh, any idea?

[ossassin]

The M995 black-tip AP .223 bullet is 62 grains. If you want more info on the .223/5.56x45 cartridge, go here (http://www.ammo-oracle.com/). This (http://www.globalsecurity.org/military/systems/munitions/556.htm) is a good site, too.

[NickSG]

.223 doesnt do that well against most types of armor anyway (although ive seen a 55 grain FMJ zip through a level III vest). I doubt even .223 AP ammuntion can get through much more than 1/2 inch of steel. All FMJ weights we tested failed to go through 3/8 inch.

150 grain .30-06 AP ammo barely managed to get through 1 1/2 inches of steel, but the FMJ of the same weight (150 grain, I think) failed to go through 1 inch.

.50 BMG FMJ (800 grain) easily penitrated through 2 inches of steel. I dont think they tested any AP ammo. If they did I missed it.

All of the above testing was done at a demonstration I saw a while ago, long before I had any interests in guns. If I could, I would offer more detailed info but I cant, since I didnt care to remember most of it. However, in my own testing, every handgun caliber I tested failed to penitrate through a level III vest and only the 10mm and .357 SIG managed to even dent a 1/4 inch thick steel plate. Of the calibers tested (.22LR, .22 magnum, .32ACP, .380, 9mm, .357 SIG, 10mm, and .45), the .22 magnum penitrated deepest in the III vest.

[Flake2m]

IIRC the reletively new 5.7x28mm round is suppossed to be quite effectice against Body armor. According to the FN website the 5.7x28mm bullet can penetrate 48 layers of kevlar at 200m when fired from an FN P90.
However, most police sevices and security forces around the world use the 9mm round, which isn't very good against body armor. So that would be the best area to start with designing improvised body armor.

[Chemical_burn]

I cant remember where but I have seen dont have it any more a video of a US marine deminstrating the effectiveness of a 700grain .50cal AP round penitrating a manhole cover at 1800m like a hot knife though butter. It was some scarry shit.

According to the site this was on the maximum effective range of a 800grain .50cal round was 4200m on a soft target (human equiped with standard boddy armor) :eek: the round doesnt even have to penitrate the armor. It carries enough kenetic energy to shadder bone and cause fatal injuries at that range. :D Thats some scarry shit.

Hell the farthest recorded kill with a .50 cal round was approximidly 2500m made by Carlos Handcock jr. During the vietnam war he used a .50 cal Mg equiped with an 8x scope to make a head shot at that range :eek: he was one scarry mother fucker. By far the best sniper in the world then or now as far as most are consirned.

As for me on consirning boddy armor I can buy military Ballistic armor at a local Army surpluse store for any where from $90 US to $150 US depending on the age and condition of the armor.

Its old and very fucking thick and somewhat comberson but shit I dont care. They even have a vest split down the middle showing the penitrating depths of several standard rounds from a .22 cal up to a .308 mag at 30m very impressive. What I thought was even more impressive was that a .22mag had a supprisingly very good penitration. The best penitrating round though was a .17-233 High Velocity rounds passed thought it supprisingly easily said the owner almost like it wasnt there. :D

[Jacks Complete]

Mr. Hathcock is (was?) certainly a great shot, but the best sniper ever? Not so sure about that. He got a great write-up, and others didn't, despite higher kill counts. Hathcosk got 80 confirmed, and 300+ probable.

"Chuck Mawhinney agrees. During nearly two years as a Marine sniper in Vietnam, Mawhinney had 103 confirmed kills and another 216 probables. No other Marine sniper in Vietnam had more confirmed kills of Viet Cong and North Vietnamese army regulars." http://www.foxnews.com/story/0,2933,65639,00.html


Anyway, the longest snipe has now gone up. IIRC, some Canadian guy sniped someone at 2430+ meters. I guess Afghanistan was barren and flat enough that targets could be seen at that kind of range!

http://www.snipersparadise.com/articles/2430kill.htm

Seems the team isn't getting a medal, as the Canadians think that people dying in a war is too nasty, and shouldn't be "celebrated"!

[AsylumSeaker]

Perhaps a way to deal with shaped charges is to put some sort of screen over the armour which the probe on the missile hits before it is at the right standoff. You could.. say: Put a foam rubber matress over you armour and then put a peice of tin plate or something on top of it. It would be better if the SC was somehow caused to detonate after it passes its standoff range but I can't figure out how to do that.

[stickfigure]

If you want a vest to stop .30cal AP try the Vietnam era Variable Armor, Ground Troops. IT's rated to stop it and these vest were made up through the 80's and can be found new for about $250-$300.
or
A Vietnam era Helicopter Gunner's Vest it to is rated to stop .30cal AP and is slightly differant than the variable armor. I have both vest and they are heavy and not flexable. The Gunner's vest has bigger plate than the Variable, but no soft later, just plates and a padded carrier.

I have a wealth of info on body armor and a stack of vests now pushing over 20, that will be for sale on eBay when I get my new camera next month.

It is near impossible to stop a .50cal with anything except and armored vehicle and that's tough. The .50cal was developed as a tank stoping round. It is capable of disabling an M1A2 Abrams if used properly and that's the most advanced tank in the world. If you are being shot at with a .50 you are probably already dead or will be shortly. If not, dig a hole, a very deep hole.

[Jacks Complete]

Since we can now upload pics to some threads, here is a section view of my armour.

Normally it should be angled so that the effective thickness is higher than if it is flat on to the threat.

As described in my opening post, I think this should stop most threats.

Using the high powered capacitor electric armour effect, the material in the center should be quite dry, to stop shorts. I would go for dry granite stomes, for reasons described below.

Ok, there are several different types of anti-armour projectile:

Kinetic energy
KE rounds kill by virtue of the speed and weight of the round. Sadly, we aren't going to stop a KE tank round with this stuff. However, multiple layers will be effective against lesser threats, such as 27mm Arden cannon rounds. I reckon this armour would be quite effectice for it's mass, as the high hardness of the granite filler means that non-AP projectiles should get utterly fucked up by it. The non-uniform nature of it means that poorly stabilised rounds will get tumbled, and hopefully stopped by the thicker back layer.

High Explosive Squash Head
HESH rounds slap a big bit of explosive on your hull, then go pop, using the shockwave to "spall" metal fragments into you, without having to hole the armour. This defeats that type of attack, as the thinner outer plate gets deformed, and hits the stones. However, the stones are quite large, with air gaps between them, so they are very poor shockwave conductors. Any that hit the inner steel will shatter, rather than defeat the plate, and the fibreglass liner (green) should hold any minor spall anyway.

Shaped charge
As most members know, these use an explosively formed jet of molten metal, normally copper, to "drill" a hole through the armour. This armour should disrupt the jet after it has defeated the first plate, as the plate is not flat on the inside. Also, the granite is randomly arranged, so causing external forces to act on the jet. Finally, as the jet reaches the inside plate, it completes the circuit, which dumps many amps of power into the jet, disrupting it completely.

Molatov/Napalm
Whilst not strictly defeating the armour, if you burn to death you have still lost. This armour defeats this type of attack by use of an air gap, and granite, which has a low heat conductivity. This means that while the outer plate gets hot, and conducts heat away, the inner layer stays cool.

[Jacks Complete]

Ok, just followed the links above.

Apparently, these are the salient points:

Military 5.56 rounds -

1967-82, M193 Ball, Copper Jacket lead bullet, weight of 55 grains
Penetrates 1mm RHA Steel


83-95, M855 Ball, Steel core and copper jacket, weight of 61.8 grains
Penetrates 3mm RHA Steel


96-now, M995 Ball, Tungsten core and copper jacket, weight 62 grains
Penetrates 6mm RHA Steel

[NightStalker]

An interesting type of armor was developed to replace concrete for ships during WWII. It was called "Plastic Armour" and consisted of several inches of asphalt poured hot into forms built around the vulnerable deck structures. It was backed with 3/16" mild steel – hardly what you'd call armor plate.

The ingenuity lay in what was mixed into the asphalt: clean, sharp, ¾" granite gravel, about 1 part to 2 parts of asphalt. Once the mixture had set the forms were taken away, and this stuff proved quite effective at stopping machine gun bullets and even 20 mm shells.

It worked because the gravel tilted on impact, pivoting inside the asphalt matrix and inducing keyholing by the bullet, which spent its kinetic energy going sideways instead of straight in. The mild steel backing flexed inward, spreading the shock over a wide area and thus preventing penetration.

When we recall that some German aircraft MGs fired ammo the equivalent of proof loads, that's an impressive level of protection. 20 mm shells were similarly defeated. Strafing attacks suddenly became less lethal, and Plastic Armour was in great demand by bridge and deck crews.

Similar armour is described in a military FM about field fortifications around the time of the Vietnam war. It was made from tar, gravel, and corrugated sheet metal and would stop shell fragments and AK bullets, so that'd be a suitable starting point to build up.

NBK wrote an article that's floating around, called Security Architecture, where he describes the use of earth berms and concrete rubble to fortify house walls to discreetly proof them against .50BMG and lesser caliber threats.

[vulture]

Very densely annealed Al2O3 is also used in armor, because it shatters upon impact, absorbing a great deal of KE.

What's wrong with Ti sheet metal? It's not that expensive.

If you really want some nicely improvised stuff, boronnitride is an option, as it can be made by BCl3 + NH3.

[concrete feet]

Admitedly, i have little to offer this thread, but i thought i'd venture to comment on the subject of gravel/stone layers in field fortifications.

This pertains more to fortifications constructed in advance of any threat to the combatant, as in home/property protection against any invading force [unlikely in this contry at present, but not so in others]. The time and resources used to construct said fortifications could be stretched out over time and procurement could thus be made less problamatic.

Stone/gravel layers for the displacement/absorbtion of shockwaves, dispersal of directed flows of penetrating material and such could maybe be enhanced by use of volcanicaly expanded mineral material such as perlite, goelite or even lavarocks or similar. These will be irregularly shaped [except in the case of geolite, which are round pelletts of volcanicaly expanded clay but better at heat insulation due to a more regular distribution of air pockets] and should be capable of displacing directed volumes of compressed air. They would be harder, but fragment more easily than, many types of gravel, due to the fact that they are mostly air but i think they could help also help counter the problem of the heat generated by the explosion. I do not know how well this would work, but i thought i would bring it up in hopes that soembody might find it useful.

There was more i wanted to write on the subject, and i will if i find the time, but for now i'd just liek to see what others think.

[edit: edited for spelling]

[Jacks Complete]

concrete feet,

don't worry if you feel you have little to add, if you have some useful ideas that aren't present in, but are related to, the thread, chip in. You won't get in trouble if you are trying and aren't stupid!

I don't think that lavarocks (pumice?) would be up to much, as they would have a very low density, and so little bullet stopping or turning ability. Having said that, it is a very light ceramic, almost. This might be worth testing.

If you have the ability, give it a go. Get a sack of pumice or whatever, and do a few comparison tests with concrete, granite gravel, etc. and let us know on the boards, in this thread.

The idea of laying in low key defences over time is pretty tricky. I haven't looked at the NBK2000 file mentioned above, but, in my opinion, it is generally better to find a good spot first and foremost, then set about making it even better.

Things like arcs of fire, river bends, tree lines, etc. tend to be critical, and so it is better to find a good place, and tune the area, rather than getting something you can't do anything about, like other houses, etc. and trying to then make the best of a bad thing.

Some of those really fancy landscaped gardens you see in films are a joke, and if i were some big league drug or (illegal) gun dealer, I would ensure that the cover, etc. worked in my favour, with sod all for any attackers to hide behind within 50 meters of the house, and subtle range markings for various lines beyond that.

My parents place has a superb defensive structure, and would stop an MBT from one direction, with any attackers coming from o'er t' hills (mad cows and rabid sheep?) could be picked off with a rifle as they cross a good 600 yards of light scrub and open field, with sod all cover.

From the other side, the same attackers would be utterly concealed, and upon the place with a few seconds notice, as the lie of the land would conceal them very well. Any attempt to "bunker" the place would be pretty obvious from one direction, but not from others.

Enough waffling.

Even if you set up walls of nice granite, etc. they aren't going to be anything against artillery or airstrikes, unless they are carefully banked to deflect blast, etc. and don't forget, gravel is effective shrapnel at close range.

In other news, I saw an interesting idea. It is basically a wall of interlocking lego type bricks, which are then filled with water or concrete or whatever, and are used as ballistic protection. IIRC, the plastic is 18mm thick walled polypropylene, and the bricks are 2x1x.5 m, and interlock so there aren't any direct paths through it. The concrete filled ones are for permanent structures, and the water ones can be drained and moved. They are the same brick, just different fillings.

Apparently, they will stop a direct artillery strike, when in the proper walled structure, two deep. They are designed mostly for stopping snipers with .5BMG knocking bits off parked jets and helicopters, etc.

Vulture,

have you ever made any boron nitride? How do you make it into a solid plate, rather than a powder?

---
The quick post ate my signature

[Flake2m]

Lets try and look at stopping bullets this way.
What has .50BMG ammo got going for it?
-The ammo shreds most conventional armor
-The bullets are pretty big
-Fairly high velocity.
-High stopping power
-long range
Correct?
Now what does the .50BMG have thats a liability?
-The weapon itself isn't hand held
-Bullets aren't as readily avaliable

If you can figure out the .50BMG this way, there might be other ways to out do this weapon.

[vulture]

Vulture,

have you ever made any boron nitride? How do you make it into a solid plate, rather than a powder?


Negative. BCl3 is a bit hard to get and somewhat nasty to work with, but it can certainly be done.

Under normal conditions it indeed forms a powder, but most of it is being used right now to coat metal substances, eg surgery scalpels. It seems to condense and adhere to metal fairly easily.

Now I know that you'll only get a thin layer, but it might be enough. It will be harder than most materials used in bullet penetrators, so it'll scratch and deform the AP part of the bullet, greatly reducing effectivity and changing it's flight path.

[thrall]

I've once seen the production of helmets.The people were using glassfiber and some resin to make the thing.It is simple.Take a sheet a glassfiber and mix the resin with some catalyst and soak the glassfiber in resin and put the layer on whatever you want to make.You can put layers over layers to make more and more and more thick.As I was told in the same manufactury that the glassfiber if thick enough can stop a bullet.The main benefit is that(what I was told) the strenth of glassfiber is more than 10 times in terms of weight.Plus one doesn't need to melt anything.you can manufature the thing at home as well.The only problem in the resin and catalyst.I'll search and post later but this interesting idea to pusue.

[Jacks Complete]

Vulture,

If it is hard to get and only makes a thin layer, it isn't going to stop a bullet in an improvised system.

Boron Nitride is ultra-hard, in its cubic form. As far as I know, it is attached to metal substrates by plasma or vapour phase deposition in a vacuum chamber. I don't know how it is grown any other way, either. As a powder, it would be useless, unless it could be sintered.

thrall,

fibreglass is very tough, and very light for how tough it is. Carbon fiber is even better, but about ten times more money. You can get kits from bodyshops/auto body repair places to do small sections, but the best way is to go to a wholesaler, and blow £20 on a litre of resin and some CSM (Cut Strand/Sheet Matting), as well as a load of release agent, wax, a roller, etc. Go on a Sunday and pay cash, is my advice, and you just might get small amounts tax free.

Now you can coat about anything with wax, then release agent, then a surface gel coat (but only if you care about the finish) and then glue layers of CSM together, rollering well, and bingo, 12 hours later you have a bullet-resistant sheet.

It is very tough stuff - some years back, I was told a story about a test at a range of 100yards, when a friend of mine shot three rounds into a plate with 7.62, and they didn't penetrate it.

Here's an idea: A common practise with boats is to use a handful of sand to roughen the surface by sprinkling some on just before it cures. Another solution might be to take the BN and use that instead. If you then layered a second layer of fiberglass over it, and so on, it might be even tougher than before.

[thrall]

Exactly,you can make any shape thats waht I was thinking.What about making Mediaval time body armor ;) .Thanks for the information that it DOES stop the bullets.The best part of this thing is that it is very lite and one can wear such suit(homebuilt of course) and can run as well :).No matelergy,all meterials commonly available,any shape,light weight,cheap;).I'm going to build it soon.But there is no way to test since I don't have any fireweapon and none of whom I know(alas! I live in India).

[vulture]

Something interesting to look into: I just found out that some ceramic suppliers will sell SiC and BN. SiC was about 20€/kg. That's a very good price IMHO. Trouble is both of these materials require quite high temperatures to be adequately sintered.

But as compressed filler, they might be worth considering.

If it is hard to get and only makes a thin layer, it isn't going to stop a bullet in an improvised system.

Boron Nitride is ultra-hard, in its cubic form.

It's also very hard when deposited in a thin layer. It won't stop the bullet, but it will deform it. A scratched AP bullet is worthless against armor, since it will deform itself considerably once it hits something, in this case your second metal layer.

[Jacks Complete]

thrall,

yes, you could do that! Not a bad idea, but take care! I have looked at, and handled, armour from around the world from various times. Most of them were designed as a halfway house between stopping arrows, and stopping bullets. The "traditional" stuff was sheet steel, generally made with one or two plates welded together in the forge. Some had a third plate, too, sandwiched in. Basically, the newer the armour, the thicker it was, until the stage, around 17thC, when they realised the bullets were too fast if they were close, and the arrows too heavy. Also, if the plate was dented (mainly by a bullet, the wearer had to unclip the armour to breathe, leaving him exposed.

There was also chainmail, but even with modern materials, it wouldn't stop a bullet, but was great for blunt swords or hammers, etc.

There was platemail, which simply linked the plates with chainmail.

A neater cross between the two was a little known type called scale or lamallar. This was first found with the Romans, who used many small plates that overlapped, and was so called because it was made up of individual scales. After the fall of the Romans it disappeared.
Many years later, it was rediscovered, and in a slightly different form. Where before the scales had only been attached at the top, like slates on a roof, and hung downwards in the same way, the newer type was made of square plates, secured via one hole in the centre. These were sewn to the backer in such a way that each plate overlapped the others, so that there was always two plates covering the backer. These plates were made from hard steel, and were very effective considering the simplistic nature of the design. It is my belief that the person who re-invented it got it right, and after his style was copied, the more common newer variant was made, which was similar, but offered far less protection for the same weight!

Anyway, enough background. For your version, I would recommend carbon fibre, if you can get it. Forget the holes through it, as you are going to be able to pass thread right through it before you coat it with resin and cook it! Next, get whatever the strongest, hardest plate you can is, be it Boron Nitride or carbon fibre/fibreglass with sand (Aluminium Oxide - grinding wheel) and layer that over the front, offset nicely as described. You will have a lot of trouble making those holes if you buy something without holes, though! They don't have to be squares, but triangles would stab when you bend, and other shapes need more cuts. Circles, of course, would never close the gaps. Now sew the lot together. You got armour! The old stuff used squares about 3.5 cm wide, to try to avoid you being punctured by a plate that got banged hard.

Of course, the old days had armour piercing arrows, which were slow and heavy, and soft lead balls doing ten times the speed but weighing a lot less. Today, we have very high speed armour piercing bullets. Your mileage may vary. I would suggest bigger plates and a tough cut-proof backer with shock padding. Otherwise you might stop the bullet, but you will be killed by the transfer of KE through the vest!

I have also heard tell of body armour that will stop .50 BMG, up close. It is a rigid shell of glass fibre, half an inch thick, which is spaced away from the body, and built into the truck that is being driven. The driver can just about drive, but the armour is effectively part of the truck!

[thrall]

I was thinking about making a copy of as you said "traditional sheet steel" armor that I saw in the museum.Since fiberglass never get daunted so no breathing problems.It can only be pearced but even then no breathing problems;).As for feet simple copy of leg guards that are used while playing hockey.But well I was only thinking of making the one for chest .That is the largest area exposed.Covering limbs is not a good idea since it will hamper agility.And about shock,Putting some sponge behind armor(between body and armor) will help?Or something else that you know about?BTW half inch thick fiberglass armor can be built at home as well(I'll make mine 1/2" thick).

[Jacks Complete]

thrall,

No guarantee on that half inch thick fibreglass!

I would recommend something a bit more high tech than sponge. Try Sorbothane, the stuff they use for shock absorbing insoles. A heavy rubber would also be good. Sponge would collapse too fast, and take little energy out. (Technically, you aren't trying to really take energy out, more you are trying to spread the impact in the time domain.)

[stickfigure]

Flake2m here in the US .50cal is really easy to get ahold of. You can actually buying pre-linked in black-tip AP at most good gunshops or pawnshops and the cheapest rifle I've seen is under $2,000 more like $1,500 which is pretty reasonable for that kind of fire-power. .50 cal is firepower that is best avoided if it's aimed at you. The average civilian won't be able to find armor to protect against it. But if you do have $100,000 to $200,000 a brave person could buy a 1960's to 70's era MBT that would help.

[Mike76251]

To stop .50 cal............forget it. Unless you want to weigh 500 lbs.
To stop RPG's........ A old trick in Nam was to put out chain link fence to detonate the round before it got around you.

[scooter12589]

quoting from the US army improvised munitions handbook
inches
5.56mm .30cal .50cal
mild steel (structural) 1/2 1/2 3/4
mild alum. (structural) 1 1 2
pine wood 14 22 32
broken stones cobble gravel 3 4 11
dry sand 4 5 14
wet sand earth 6 13 21
(ball ammo at ten feet)

[nbk2000]

That was back in the '50's or 60's.

Ammunition has vastly improved since then, so I'd double those figures, especially if I was on the receiving end. ;)

[Anthony]

I'd forget polycarbonate unless you need it for transparency. It's much more expensive than mild steel and much less effective. That and mild steel won't go brittle and subsequently shatter from exposure to sunlight!

Penetrating a manhole cover is impressive, but remember that manhole covers are cast. So much less effective than mild steel, which is much less effective than RHA.

Posted by Jack's Complete:

"I am amazed that the Tungsten 5.56 went through 4.5" of aluminium"

I think that what PHAID meant by: "A .223 SS109 round will penetrate 4 1/2" Al plates and mild steel up to 1/2" was that the round would penetrate 4 x 1/2" plates, i.e. 1" total, rather than 4.5".

AFAIK, bullet resistant glass (for armoured cars etc) are all glass (what looks like one thick sheet rather than mulitple laminations), save for a thin polycarb backing which stops spalling. Materials and construction might vary from manufacturer to manufacturer though.

Armoured cars seem to be quite good at what they do. I don't recall any stats about 50BMG AP resistance though! Surprisingly good against anti-tank mines though.

Pumice is excellent at absorbing blast energy from explosions. Obviously a good backing is required though.

[PHAID]

Yes you are correct Anthony it was 4 1/2" plates and the only reason i counted it as penetration on the last plate was because the tungsten penetrator tip was sticking out 1/16"

I didnt catch it earlier or i would have tried to reword my post to better explain

[probity]

Kind of off topic but very interesting none the less...
http://www.armedforcesjournal.com/bullets/

"During a telephone interview last month, Thomas said the bullet he fired struck one of the attackers in the upper left quadrant of the buttocks, killing him immediately. Under most circumstances, a 5.56mm bullet striking a person’s buttocks wouldn’t be expected to create a fatal"

"Designed to release maximum energy in soft tissue, the “armor-piercing limited penetration” ammo will bore through hard targets, such as steel and glass, but will not pass through a person or even several layers of drywall."

[Jacks Complete]

probity,

I think this is just the usual drivel. The reason the 5.56 doesn't expand is because it is against various treaties to use expanding ammo in wars. That's why they use the stabilisation trick instead. Also, the guy didn't really get shot in the buttock. Sure, that is where the entry wound was, but it hit his stomach and gutted him, just like you would expect for a quartering target like that.

Also, hitting someone with body armour (standard stuff) will cut through them the same as anyone else from 100 yards. Besides, do you know anyone with "ass armour"?

[silverleaf]

If you are looking to defeat projectiles, then try rounding the armor, or by angling it like on a tank, this increses the chance that the round will glance off and that you don't have to rely solely, on the strength of the armor material. This was pioneered by the Russians on the T-54 in world war two, it really screwed with the german panzers, seeing as how they kept shooting, but the soviets kept coming. I hope that helped a little.

[Cheese]

There a major problems with attempting to stop ANY kind of munition specificly designed to penetrate armor. Primarily because unless your willing to go to extream lengths, its already been done, and its already been defeated.

For example, with most kinetic energy armor piercing munitions, the principal is to place as much stress on the point of impact as possible(Stress(Nm^-1) = Force( / Area(m)). So they make the projectile pointed, and dense, in order to maximise the force over the minimum area.

If you ever find yourself up against a REAL armor piercing round(http://remtek.com/arms/steyr/amr/amr.htm) then almost nothing you can make(a reactive armor system might have a chance) will save you.

[nbk2000]

Chaotic armor can defeat 30.06 AP bullets at point-blank range, while still being vest-able. Patented, even.

Utilizes a matrix embedded polymer layered with spectrashield. The bullet impacts the matrix and, by altering the direction in which the bullet travels by even a minute fraction, sets up destructive shearing forces within the bullet that causes it to disintegrate into fine dust. :)

Remember, bullets are rotating at like 250,000 RPM, so even a slight unbalancing within the bullet causes incredible stress to it. This is why hot-rod varmit rounds sometimes disintegrate in mid-air.

This armor principle is being developed for the "Land Warrior" project armor. But, as effective as it might be against projectiles that are spun by rifling, you could defeat it by going retro, back to smooth-bore projectiles.

Just like tank KEP's aren't spun, a smooth-bore firing saboted flechettes would be able to penetrate chaotic armor, as the penetrator might be deflected, but there'd be no chaotic shearing to disintegrate it. :p

[JoeJablomy]

Many things need to be said. But first, all due respect to NBK, but the rotational forces on a bullet are nil compared to the impact forces. Bullets may be spinning incredibly fast, but are still only going one rev in 10 or 15". Think of the total velocity of a particle on the edge of a bullet. The rotational component is tiny compared to the forward component. Every time a ricochet makes that whirring noise as it bounces off someplace, it's almost certainly because it's direction has been altered in such a way that it's no longer spinning on axis.

Now: Ceramic armors absorb some energy by fracturing. Specifically, they form radial and shear cone (opening away from the direction of impact) cracks. A mass of fractured cemaic is thus pushed against the rigid backing. Those of you who adhere to the nearly correct belief that sharp points are necessary for penetration will understand how this affects the projectiles ability to penetrate the backing.
Even ceramic bathroom tile will stop some bullets if properly backed. (specifically, I was fucking around one night and found that tile would stop .22lr out of a rifle when backed with wood. Most of the time. When backed with wax to test the hypothesis that rigid backing was needed, the result was a 1/2" hole in the wax with manyy bits of tile embedded in the sides. I believe the bullet shed the mass of tile it pulverized while passing through the wax.) Somewhere on the net there's some experience by a kewl who made a vest with tiles wrapped in duct tape and backed with cardboard. I'm surprised it could do it with cardboard, but if it had double layers of tile then one layer could have backed the other. The duct tape is probably a good idea for stopping spall.
Ceramics also blunt projectiles significantly, especially soft ones, but even a tungsten core will be significantly less effective if it's nose is expanded to 1.5 times it's original diameter. Note that this is irrelevant to long-rod penetrators. At the velocities of tank rounds and above, it is said, and probably accurately, that dynamics overcome the strength/hardness of any materials involved and behavior is determined mostly by fluid dynamics.. The heads of long-rods mushroom out anyway, and one of the real reasons DU works better than tungsten is that the mushroom shears off around the sides and leaves a 'sharper' head with less contact area.

Anyway, a good 2-layer armor would be a plate of a hard ceramic like alumina or the alumina/TiB2 SHS composite that's been spoken of a lot lately, and a thick plate of hardened grade 5 titanium or alloy steel. Boron nitride (By which you mean CUBIC boron nitride, not normal BN) is not a good idea, since it costs way the fuck too much. Alternatively you could use a thin plate of hard metal and a thick layer of high performance fiberglass.
To stop rifle rounds this would probably be 1/2-3/4" thick. For reference, I saw a composite armor structured APC on paper that was designed to stop .50 rounds; it had about 1.5" thick tiles and 2" thick fiberglass behind them with 1/2" fiberglass on the outside as a spall shield. It could probably stop a .50 SLAP.

Speaking of composites, there are three ways to arrange the reinforcing fibers of a composite: woven plies, 3-dimensional weave, and unidirectional. There is also the other, non-woven 'cloth' with fibers running in all directions randomly, but by all accounts it's crap. I have a nagging fear this is the "scm" referred to above. Anyway, 3-d weave and unidirectional have about the same ballistic impact resistance, which is somewhat better than woven plies. The problem with 3-d of course it it's a huge pain in the ass to make, so I'd go with unidirectional (alternating plies, probably by 30 degree increments) if I could get my hands on oven cure unidirectional prepreg tape. It's starting to become available.

As for suspending body armor on sorbothane, it's probably not necessary. The armor will absorb most all of the kinetic energy unless it dents in and hits you, which it shouldn't if it's rigid. You will recall that for a given momentum, the energy must be Greater for Smaller objects according to how small they are (masswise). This is why a gun does not recoil with the same energy as its bullet, but only a fraction therof, equal to the mass ratio between the gun and projectile. The bullet must transfer its momentum to the vest, but if the vest weighs more than a few pounds it won't hit its wearer that hard. Helmets don't weigh very much, and they have suspension systems to transfer the impact impulse to the wearers' heads as smoothly as possible.

One big problem with armor, though, it how hot it gets inside it. Sorbothane would make that worse. If you're afraid your breastplate will dent in, maybe isolating it on a few blocks of foam rubber with about a 1/2" air gap would be best. Possibly even with a battery powered CPU fan to force air through it, since you may as well go all-out. You could use a bunch of thin walled flexible plastic tubes held under low pressure by a fan as the actual isolation pad.

One other comment: I have yet to hear exactly what the theory is behind electric armor, but I do know a 'heavy duty spark generator' is not nearly adequate. Ever heard of a 'pulsed power supply?' That's what you'll need. We're not talking about anything that can be called a 'spark generator', but more like a 'giant capacitor bank suitable for a large rail gun.' This is why electric armor, like ETC and rail guns, is not presently on European or American military vehicles. Irregular shapes will also not have any effect on shaped charge jets because only the bit at the very front will even touch the irregular surface; that bit will be smeared around the part of the bore hole it makes, producing a channel larger than the jet itself. The remainder of the jet will continue to penetrate the armor. ERA can disrupt jets and displace part of the jet after the tip detonates the explosive, causing fragments to hit different places and not go as deep, but ERA uses shockwaves you can't get much of any other way.

[Jacks Complete]

Even ceramic bathroom tile will stop some bullets if properly backed.Very true. Dinner plates are better, though, in my experiance.
There is also the other, non-woven 'cloth' with fibers running in all directions randomly, but by all accounts it's crap. I have a nagging fear this is the "scm" referred to above.Yes, it is, but it is CSM => Cut/Chopped Strand Mat. Pretty cheap, but useful for most low-type apps. Bullet resistant clothing is NOT one of those, but it would suffice for backing plates and the like.

As for suspending body armor on sorbothane, it's probably not necessary. The armor will absorb most all of the kinetic energy unless it dents in and hits you, which it shouldn't if it's rigid.That is what any soft body armour does, hence the suggestion. Obviously not a problem with rigid armour, unlike moving!

One big problem with armor, though, it how hot it gets inside it. Sorbothane would make that worse. If you're afraid your breastplate will dent in, maybe isolating it on a few blocks of foam rubber with about a 1/2" air gap would be best. Possibly even with a battery powered CPU fan to force air through it, since you may as well go all-out. You could use a bunch of thin walled flexible plastic tubes held under low pressure by a fan as the actual isolation pad.Good idea. Keeps you warm when waiting, and cool on the move!

One other comment: I have yet to hear exactly what the theory is behind electric armor, but I do know a 'heavy duty spark generator' is not nearly adequate. Ever heard of a 'pulsed power supply?' That's what you'll need. We're not talking about anything that can be called a 'spark generator', but more like a 'giant capacitor bank suitable for a large rail gun.' This is why electric armor, like ETC and rail guns, is not presently on European or American military vehicles.Not quite true. The reason no-one uses electric armour is because it was only invented about last year. It works using a large capacitor, and only doubles the electrical load on a small IFV, while making it immune to any form of shaped charge.

It works because the white-hot metal has a very low resistance, and forms a dead short, which causes a huge current to flow, which makes the jet act like a quick-blow fuse.

Irregular shapes will also not have any effect on shaped charge jets because only the bit at the very front will even touch the irregular surface; that bit will be smeared around the part of the bore hole it makes, producing a channel larger than the jet itself. The remainder of the jet will continue to penetrate the armor. ERA can disrupt jets and displace part of the jet after the tip detonates the explosive, causing fragments to hit different places and not go as deep, but ERA uses shockwaves you can't get much of any other way.Irregular shapes don't help as part of the overall design, but a very ridged surface will, as it disrupts the forming of the explosive shock cone and the creation of the jet, due to upsetting the stand-off distance, and the path distances. Stand-off wire mesh has been used, as has the low-tech idea of having matresses strapped to the tank!

I was, however, talking about irregular shapes within the armour itself, in the form of other density materials, such as ceramic rods, which resist the jet, and push it off line slightly. This reduces the effectiveness a long way, similar to blunting a penetrator. This is used in Chobam type armour, and the ceramic helps with rod type penetrators as well.

A way to beat a long-rod penetrator would be to use a set of shaped charges that were angled away from the armour, but not normal to it, so that when it hits, the charge detonates, cutting or seriously damaging the rod, or even shattering it, or, best of all, knocking it off line, so that the rod hits sideways, and fails to penetrate. This would require some development work, however!

[nbk2000]

Joe, AP bullets are designed to withstand impact forces, but not angular shearing.

Bullets are essentially tubes. Strong in compression, weak in lateral, like empty soda cans. You can stand on top of a soda can, but don't try that on the side, as it'll collapse.

Also, there's a reason why it's called "chaotic" shearing, that being that it's *chaotic*ly applied and not even. The armor induces directional changes in different parts of the bullet, so that parts are heading in different directions at once, causing the bullet to tear itself apart.

Much smarter people than you or I have figured this out already, so denying that it works doesn't keep it from working. :)

[JoeJablomy]

A search for "chaotic armor" doesn't seem to have turned anything up, but the theory still sounds flawed, unless these "chaotic forces" are applied by embedded high explosives. An AP bullet is rather the opposite of a tube, structurally.

Jack: I don't know how long the jet-bursting electric armor you refer to has been around, but American defense research has included some kind of 'electric armor' for the past several years. Yes, this approach is easier than the kinetic version seemed to be, but it's still going to need a bigass capacitor bank. In the one of the articles that came up in my search, it compared this system to ERA by saying it would add "only" a few tons to a vehicle, whereas ERA would add a few tens of tons. This may be an exaggeration, but the fact stands that you need a capacitor that can destroy not a bridgewire but something like the 14GA copper used to wire your house. The leads of the capacitor bank will therefore have to be about 1/2" wide to handle the current without vaporizing, and the electrode plate will have to be thick enough to transport this current to the impact point.

Furthermore, have you ever seen a computer model of a hollow cone charge detonating? The jet is almost entirely formed before it leaves the warhead, most of the compressing/extruding happens at about the front of the charge itself and the only other function of standoff is to alow the jet to stretch to the greatest length before beginning to consume itself on the armor (the jet, which is solid, by the way, liquids just get blown into useless clouds, has a velocity gradient such that the tip is travelling away from the tail; the reason the standoff has an upper limit is that the jet breaks up, another thing it would not do if it were liquid). The relevance of this is that armor geometry has very little effect on jet formation. The reason standoff cages work is probably that most of the time the RPG gets snagged before its nose fuze hits anything hard and the grenade doesn't even go off. I have yet to hear a truly reliable account of exactly what Chobam armor really is, but I can definitely tell you that the only property of a material that really matters to an SC jet is its density, and the irregular changes in hardness made by embedded ceramic rods will not mean much. You cannot deflect the jet. The tungsten rods might do something to it, but I'm willing to bet that ceramics will act like hard rock. Shaped charges are pretty good at going through rock.
http://www.logwell.com/tech/shot/index.html
I guess I should try to sum up the understanding of shaped charges I have developed to explain, for future reference, why the jet cannot be deflected. A shaped charge jet is a rapidly deforming piece of solid copper that has so much energy distributed so unevenly along it's length that it undergoes spaghettification just from its own irregular momentum. It behaves somewhat like a jet of water would at more normal velocities, although its tensile strength and other characteristics do play a part in determining when it begins to break apart. When the tip, which may be travelling several times as fast as its tail, impacts the surface of the armor, it is said in many places that the surface in contact with the jet has such velocity imparted to it that it opens to a diameter several times as big as that of the jet, and that the part of the tip that imparts that velocity is spread all over the inside of the bore. Obviously, from kinematics, the velocity to which the armor material is accelerated to, both in front of and to the sides of the jet, depends on the mass (thus the density) of the material. Denser materials resist jets better. Strength is irrelevant.
I guess the operative part of this is, the front part is always consumed and smeared all the fuck over the place. Introducing it to a funny surface, which it will obliterate anyway if it's standing in front of it, will perhaps affect which way that very front part splashes, but will have no effect on the remainder on the jet at all.

Sorry about the lecture, but it's the only way I can come up with to explain my thoughts on the subject.

As for the active defense system with shaped charges, you mean linear shaped charges, right? They might be able to weaken the rod and cause it to buckle.

[nbk2000]

A search for "chaotic armor" doesn't seem to have turned anything up, but the theory still sounds flawed, unless these "chaotic forces" are applied by embedded high explosives. An AP bullet is rather the opposite of a tube, structurally.


Your search skills are weak!

I found it as the 9th listing on the first page of results on Google, using just the generic term. Using more specific terminology, and using only words I've used in my description of it (not anything pre-known to me), I got it as the forth result.

Remember, just because you don't find it in 10 seconds worth of Googling (although I did :)), doesn't mean it doesn't exist. ;)

If you still can't find it, just admit it here and I'll post the URL so everyone can see it for themselves.

Also, not all results pop up on the first page, like with the patent search. It was #64 there.

So you're either impatient, or inexperienced, when it comes to searching, but neither one is my problem.

Anyways, it's not theory, as its now fact, having been built and tested, and licensed for production with the US military.

And please break up your post into smaller paragraphs than you have been. It's difficult to read these huge text blocks in one go.

[Jacks Complete]

JoeJablomy,
What can I say?

As far as I know, the jet is not solid copper, it is semi-liquid. Since it is very, very hot, and explosively formed, it is under enough pressure to not boil away. IIRC, it is about 6000K. "Limited spalling is a telltale characteristic of Western-manufactured weapons designed to defeat armor with a cohesive jet stream of molten metal. In contrast, RPG-7s typically produce a fragmented jet spray." - http://www.armytimes.com/print.php?f=1-292236-2336437.php

http://www.danskpanser.dk/Artikler/power.htm will tell you a bit about the armour, as will http://www.theregister.co.uk/content/54/26728.html. Invented about 18 months ago.

If you want to post some links to correct me, I will read them.

Regarding the use of a trauma liner for vest, see http://www.roguesci.org/theforum/showthread.php?p=58280#post58280 , where the denting of the armour is clearly mentioned.

NBK2000,

please tell me how you avoided the millions of roleplaying gamer pages when searching for "chaotic" - I blanked out nine terms, but obviously not RPG, and got some really interesting stuff (which may get posted after I check the site for duplicates) but nothing worth much on "chaotic armour".

[akinrog]

While searching for bulletproof vests I found the following link through google.

http://www.post-gazette.com/neigh_south/20030611sbulletmainb4p4.asp

This vest is claimed to be repelling AP rounds. While traditional soft vests stop /catch the bullet, this vest is claimed to be "pulverising" it by means of so called hypersonic compression waves, thereby never allowing the projectile to reach the target! Anyway it was an interesting read. ;)

While I was researching the bulletproof vests on the net, I came across a material called spectra armor. More researching into it, I determined this substance is actually polymeric compound called UHMWPE (Ultra High Molecular Weight Polyethylene), a thermoplastic polymer. This armor material is much more stronger than kevlar and another advantage it is castable though casting weakens its stopping power and strength (since it deteriorates its crystal structure).

While kevlar is hard to spin since it requires special equipment to spin it (you have to either boil kevlar with sulphuric acid to soften it which impairs its performance or use special substances /catalyst (I am not sure which) to keep it liquid crystal state during synthesis and after spinning the fibers baking the fibers to render them to solid and rigid state), Difficulty in handling kevlar (in terms of converting it into a fiber and then fabric and finally a ballistic vest), renders it hard for improvised vest applications. In addition, using used ballistic vests is a little bit dangerous and tricky since performance of a used kevlar vest may be very impaired and I even do not mention about impossibility of finding such vests in underdeveloped countries)

As I stated above, UHMWPE is thermoplastic substance which can be molded into shape. This makes it ideal for new type of ballistic vests though it is already used in medical field.

In addition, AFAIK kevlar is vulnerable to angle shots and multiple shots, while spectra armor vests are one piece items which can resist multiple shots and angle shots better then kevlar vests.

Once I had a link to synthesis of UHMWPE, but I cannot find it now.

Now idea is SWIM may make a composite sandwich archaic type armor which consists of layers of carbon fiber and UHMWPE. IMHO this type of vests might be equal to that of commercial vests even if not better. Rgrds.

[nbk2000]

In Google, type in:

chaotic armor rifle

And that brings it up as #9. :)

Using:

chaotic armor rifle "armor piercing"

Brings it up as #4. :D

The pdf contains the patent number.

The name of the contractor in the pdf brings up results at www.dtic.mil/ndia/ where the contractor posted a powerpoint presentation about it.

Amazing what you can find when you LOOK for it, rather than expect it to be spoon fed to you, like I just did. ;)

[Jacks Complete]

NBK2000, do you mean http://www.eng.auburn.edu/~hthomas/Ballistic.PDF ?

Doesn't that diagram look *really* like my one? Using the odd geometric shapes to deflect the nose, and turn the round sideways, thus increasing the odds of stopping it.

Looks like something you could try at home, too. I was talking about larger stuff, but very hard ceramic or rock would certainly do the trick. Shame it doesn't say what the deflectors were made of for this test. To be honest they look like steel ball bearings, on a solid backing with raised welts.

I would say that there is a whole load of pseudo-science in that report - it was probably written to get more funding from someone! The fancy "science" words behind the fact it works are bizarre. "Generation of multiple simultaneous paths" is a weird one - the simple fact is, there is only one path taken, from the many possible ones. The side torque they put on the nose is in a random direction, sure, but so what? I would be interested to see what happens with a non-perpendicular strike, too. What I can't understand is how they are defeating an AP round by having it destroy itself in such a short distance. I think they are cheating, and making it non-flexible.

Any other thoughts?

This might be handy, too:
<table border=1><th>NIJ Standard Ratings</th><th>01.01.04</th></tr>
<tr><td>Velocity (Ft/Sec)</td><td>Weight (Grains)</td><td>Projectile Description</td><td>Caliber</td><td>Threat Level</td></tr>
<tr><td>2880</td><td>166</td><td>Armor Piercing</td><td>.30-06</td><td>IV</td></tr>
<tr><td>2780</td><td>148</td><td>Full Metal Jacket</td><td>7.62 mm NATO</td><td>III</td></tr>
<tr><td>1430</td><td>240</td><td>Jacketed Soft Point</td><td>.44 Magnum</td><td>III-A</td></tr>
<tr><td>1430</td><td>124</td><td>Full Metal Jacket</td><td>9 mm</td><td>III-A</td></tr>
<tr><td>1430</td><td>158</td><td>Jacketed Soft Point</td><td>.357 Magnum</td><td>II</td></tr>
<tr><td>1205</td><td>124</td><td>Full Metal Jacket</td><td>9 mm</td><td>II</td></tr>
<tr><td>1055</td><td>180</td><td>Full Metal Jacket</td><td>.40 S&W</td><td>II-A</td></tr>
<tr><td>1120</td><td>124</td><td>Full Metal Jacket</td><td>9 mm</td><td>II-A</td></tr>
<tr><td>1055</td><td>95</td><td>Full Metal Jacket</td><td>.380 ACP</td><td>I</td></tr>
<tr><td>1080</td><td>40</td><td>Lead</td><td>.22 LongRifle</td><td>I</td></tr>
</table>
http://www.usbulletproofing.com/Ratings.htm gives somewhat more complete ratings, for Underwriters Laboratory 752 (UL 752) and the National Institute of Justice (NIJ), as well as some other interesting stuff.

[nbk2000]

Yes, that's the link.

There's nothing "psuedo-science" about the phrase that you quoted. It simply means that the bullet disintegrates, as various parts of it go in different directions. :)

You spend enough time reading the stuff written by defense contractors and it starts becoming second-nature to understand what they really mean.

See, why say "It goes BOOM when you push the button." when you can say "Upon activation of the manually-acutated MITL command detonation circuit, the energetic material releases a copious amount of potential energy in a highly exothermic reaction.", and make yourself sound so highly intelligent that the military would be fools not to use your latest "vunder veapon". ;) :D

If you read the patent, you'll see that it IS steel ball bearings in the picture, as the material is simple to get, and is as hard (or harder) than the projectile it is intended to stop.

While it's likely not to be feasible (yet) for a flexible vest, though inserts are still practical, there's no reason you can't use the principle to uparmor your car, as vehicles are flimsy to rifle fire.

Oh, and I remember reading about a test conducted by a cop magazine, where they tried shooting vehicles with various types of weapons to see what would pass through them.

The interesting thing I got out of it was that pistol caliber bullets wouldn't penetrate through the thread of car tires, either bouncing off or getting stuck in the rubber, without actually penetrating. :o

Tires are free for the having. :) Cut, overlap layers so there's no gaps, and fix into place.