Home made body armor, amazing

[Dolomite_supafly]

This is not me although i have tested a lot of floor tiles.

 

http://www.youtube.com/watch?v=SXmyCfB_k5I

 

For what it cost him it works very, very well.

 

Dolomite

[Randall53]

I bet the shock wave would put him on his butt!  But then, he would live to drink beer again though!

Edited March 11, 2013 by Randall53

[Dolomite_supafly]

Actually the bullet hitting the person is no harder than the recoil of the gun shooting it.

 

Dolomite

[scoutfsu]

I'm going to disagree.  In 2007, I took an AK round to the rear ESAPI, lower right quadrant and it knocked me to me knees.  It did not penetrate the ESAPI but deformed the rear and messed up the soft armor.  I had a very ugly fist sized bruise for weeks and for a few days, it hurt to breathe deep.

 

Is there some kind of science that I'm missing behind your statement?  Because that shit definitely hurt me more than firing a weapon.

[Caster]

THe science is Newton's third law of motion.  For every action there is an equal and opposite reaction.  It's what tells us that hollywood is BS.  When someone shoots someone and it blows them off their feet???  For that to happen the recoil would be equal to that.  I know nothing of physics but I would say the reason you felt such an impact is the equal amount of force being focused into such a small area.  ...but what do I know.  

[scoutfsu]

Interesting.

[Dolomite_supafly]

Probably because the corner of the plate dug in or something. I worked with a person who took a x39 round center mass in the back and never knew he had been hit. Only later did they notice the hole.

 

Dolomite

[tennessee01tacoma]

I'm going to disagree. In 2007, I took an AK round to the rear ESAPI, lower right quadrant and it knocked me to me knees. It did not penetrate the ESAPI but deformed the rear and messed up the soft armor. I had a very ugly fist sized bruise for weeks and for a few days, it hurt to breathe deep.

Is there some kind of science that I'm missing behind your statement? Because that #### definitely hurt me more than firing a weapon.

When your shooting a gun you have the rifle stock against your shoulder the rifle never got to fully accelerate, and you brace for impact. 2 things you cannot do on the bullet end.

Think about a shooting a rifle and just allowing it to fly back and hit your shoulder it would hurt like hell. Edited March 12, 2013 by tennessee01tacoma

[zgunbear]

Would be a way to "armor" a vehicle.

Wonder how much a plate weighs?

Line the floor and the sides of the body with them

Edited March 12, 2013 by zgunbear

[Independent_shooter]

I would imagine on the rifle end the majority of the recoil/impact would be absorbed by the gas system/buffer tube etc. I'm sure if you felt the full force of the bolt cycling back into your shoulder, it would feel too good.

[TMF]

Probably because the corner of the plate dug in or something. I worked with a person who took a x39 round center mass in the back and never knew he had been hit. Only later did they notice the hole.
 
Dolomite

Same here. A guy I worked with was hit twice in his plate at point blank and didn't know it until after the raid. Surely some adrenaline played a part there, but he also wasn't injured so I believe it is probable that he didn't feel it considering the circumstances. I've never been hit in the plate, so I don't know, but seeing hit ceramic plates it would seem as if it would cushion the hit considerably compared to soft armor and Kevlar, especially since the energy would be transferred to the whole of the plate (since it is rigid) as opposed to something that gives.

[KaNuckles]

There has to be more to it. Otherwise how could you push a car and wouldn't firing a gun likely break your collar bone? At least it would seem that way.

Edited March 12, 2013 by KaNuckles

[Jonnin]

concept of sharp... push a needle into you with 1 pound and a spoon which hurts? its distributed over more surface.

[TMF]

concept of sharp... push a needle into you with 1 pound and a spoon which hurts? its distributed over more surface.

Yup, physics.

Think about it like this, if you put a water balloon behind a ceramic plate and shoot it with 7.62x39 the balloon should remain intact. If you put soft armor (soft armor capable of stopping 7.62) in front of the same balloon it will pop when shot, although the soft armor won't be penetrated.

[KaNuckles]

Still doesn't explain how a 250lb man can move a 2500lb car. Or why a barret doesn't break the shooter's shoulder. 2000-3000 ft/lb of energy into your shoulder without breaking?  I think path of least resistance has a little to do with it. The energy is mostly directed out the barrel because it offers the least resistance so most of the enrgy is transferred to the bullet. What about this. If your AR had a buttstck the size of a .22 cal bullet, would it do the same damage to your shoulder to shoot it as it would to be shot by it? This is very interesting stuff.

[Jonnin]

Still doesn't explain how a 250lb man can move a 2500lb car. Or why a barret doesn't break the shooter's shoulder. 2000-3000 ft/lb of energy into your shoulder without breaking?  I think path of least resistance has a little to do with it. The energy is mostly directed out the barrel because it offers the least resistance so most of the enrgy is transferred to the bullet. What about this. If your AR had a buttstck the size of a .22 cal bullet, would it do the same damage to your shoulder to shoot it as it would to be shot by it? This is very interesting stuff.

 

normal force.  2500 pounds to lift isnt the same as 100 pounds to roll it. 

barret is compensated in several ways to reduce recoil.  Put a 50 in a BA rifle and try it....

if you had a .22 round nosed steel rod for a stock and shot it, you will sprout a hole, yes, assuming your 223 isnt compensated, but it is (buffer tube, spring, etc).  It may or may not break the skin?  Depends on the rifle.  Inertia, mass of the gun matters too. 

Edited March 12, 2013 by Jonnin

[TMF]

Still doesn't explain how a 250lb man can move a 2500lb car.

Well that analogy doesn't quite work... let's see him move that 2,500 lb vehicle when the tires are flat. I've moved 10,000 lb pallets off the back of aircraft by pushing them on rollers, but I couldn't move that pallet if it was just sitting on the ground.

In a rifle the firearm is absorbing the explosion inside the chamber, so the heavier the gun the lighter the recoil, as the energy is being absorbed by the weight. For example, I've fired a R700 M24 which has quite a bit of weight to it due to the stock and barrel. I fired the R700 my relative has in the same caliber which had a lighter barrel and real light stock and the recoil was far greater.

When a person is struck by a round of a certain weight and speed, much of the energy of that round is immediately transferred to the person. If the round is stopped by armor, all of the energy is transferred. Depending on the type of armor that energy could be transferred evenly enough that the felt impact would be minimal. Now, if that same impact hits your body there are more things going on than just energy transfer. You're also dealing with pain and trauma, which is why you see folks fall to the ground almost instantly some times, but that isn't due to being "knocked down" as it is sometimes put. Most folks I've seen shot crumpled forward rather than fell back ala Hollywood. The one guy I've seen hit with a .50 didn't fly back at all. In fact, when you think about it, so much of the energy from that round isn't even transferred to the recipient because it is still moving at a high rate of speed even once it passed through the guy.

[BigK]

The reason the gun recoil vs bullet impact seems to not make sense is the missing part of the equation.

Using a .308 as an example, you're pushing a 150 gr bullet at 2800 fps. The gun actually does have an equal rearward momentum into your shoulder, but it's soooo heavy compared to the bullet.. So, to balance Newton's conservation momentum formula, that 8 pound gun (7000 gr/lb) weighs 56,000 gr, so it only has to be moving at 7.5 fps (I originally said 2.4, but forgot that was yards, not feetactually yds/s).

150gr bullet x 2800 fps = 56000gr gun (8# x 7000gr/#) x 7.5 fps

That's why those damn polymer stocks on a Mosin will mess you up! Edited March 12, 2013 by BigK

[monkeylizard]

What BigK said. F=MA or Force = Mass x Acceleration.
 
The key here is mass. Caster is correct about Newton's 3rd law. There is an equal amount of energy pushing against the rifle as there is pushing against the bullet. But that energy is pushing against a 55gr bullet on one side, and  8-10 pounds of rifle on the other side. It's why we feel less force in the form of recoil when shooting a heavier gun over a lighter gun using the same round and all other factors being equal.

 

So if you convert the 150gr bullet in BigK's example to grams then multiply it by 2800, that gives you the force (well, for science, you'd change it to meters/sec first).

Then convert the mass of the rifle to grams and multiply it by 2.4.

That would give you the force of each object.

 

The area of impact affects how the energy is transferred. All kinetic energy transfers at the point of impact of 2 objects. That's why a hypodermic needle penetrates the skin with very little force, but a boxing glove hitting you with the same amount of force is nothing. It's the same amount of force, but the focusing of that force causes more trauma to the body. It's why bullet shape matters in ballistics. It's not just about aerodynamics.

Edited March 12, 2013 by monkeylizard

[scoutfsu]

Lots of learning here. Appreciate the answers.

[klamb5]

Had a DI in basic that would put a AR up against his crotch and fire to demo the amount of recoil, now with that being said he had a fellow DI with a sadistic side that removed his buffer tube dang funnyist thing I ever saw that I new not to laugh at . That s what you call felt recoil

[Dolomite_supafly]

If a gun weighs 8 pounds and firing the bullet moves the gun say 1 inch under free recoil. That same bullet fired into a target that weighs 160 pounds will move that target 1/20th of the rifle. The amount of KINETIC energy is exactly the same.

If the 30 pound Barrett recoils 6" as it fires into a 3000 pound vehicle the vehicle will move 1/100th of 6". These are all assuming there was equal amounts of resistance. To move the vehicle 6" it would require 100 shots.

Dolomite

[Dolomite_supafly]

I will try to find the video. There is a guy being shot with a 308 at point blank to prove the armor works. He does not get thrown back like one would think with the amount of FPE a 308 has.

I do not believe FPE and kinetic energy are the same.

Dolomite

[Dolomite_supafly]

Here it is
http://youtu.be/aaS_2l8nGdg

[TMF]

Here it is

I would add that the type of armor this guy is wearing is designed to absorb energy very well as plates are overlapped to transfer energy from one to the next. I'm surprised he even described it as a "punch" since enough of the energy was absorbed that he would only feel the resonant force from the strike.

And that dude's shorts are distracting. My wife wouldn't let me leave the house like that.