Steel core flew over my head

There has to be more to it than just energy.

That photo I posted above is AR500 armor plate. The paint scuffs are from M2 Ball from a M1 Garand, 147 gr FMJ at ~2800 FPS. At 100 yards, it is down to ~2400FPS, yet still has 2231 ft-lbs of energy.

The craters are from a 55 GR Blitzking from a 243 at ~3500 FPS. At 100 yards, it is down to ~3100FPS and has 1174 ft-lbs of energy.

So how does the lighter bullet with ~53% of the energy actually damage the armor plate?
 
I had a scary one once shooting a steel pig at about 100 yds with a .223 FMJ. The bullet went through the flap of fabric on the pants I was wearing and hit the zipper on the front of my pants. It sure did smart!! Luckily no real damage was done, but I was afraid to look for a while.
 
As said, plates should be angled top-forward so that frags are directed downwards into the dirt. Easily done by hanging from the back side of the plate, it's own weight will naturally cause it to hang in that manner.

I won't (and the ranges we frequent, won't allow) shooting centerfire rifle cartridges at less than 200 yards, and if you BYOS (bring your own steel) they won't allow anything other than AR500.

Cratered steel is dangerous at shorter ranges.

Bullet fragmentation/deflection on a flat-surface, down-angled steel plate is predictable.

If a bullet hits a crater, that goes out the window. It can, and will, go anywhere as you found out.

AR500 plate is not that expensive, and I don't see the sense in using anything else. We've got thousands of hits on our plates- including some smacks with a .50 BMG (not ours) at 600 yards- and not a single divot anywhere-
 
emcon, that is all there is to it. High amounts of kinetic energy, which is a factor of velocity instead of mass, cause huge amounts of damage to anything they strike. High mass low velocity imparts greater momentum. That is why your High velocity 22 caliber rounds cratered the steel, displacing and tearing out metal, while a .44 magnum would have simply knocked it out of the park. KE is expended on the exact point of impact, not spread out as a big hit, or push.

Here are some things about Kinetic energy weapons as applied to military armor.

The principle of the kinetic energy penetrator is that it uses its kinetic energy, which is a function of its mass and velocity, to force its way through armor. If the armor is defeated, the heat and spalling (particle spray) generated by the penetrator going through the armor, and the pressure wave that would develop, ideally destroys the target
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The modern kinetic energy weapon maximizes the stress (kinetic energy divided by impact area) delivered to the target by:
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maximizing the mass - that is, using the densest metals practical, which is one of the reasons depleted uranium or tungsten carbide is often used - and muzzle velocity of the projectile, as kinetic energy scales with the mass m and the square of the velocity v of the projectile
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If you will read those correctly you will see what I'm trying to say. A military penetrator is a hypervelocity round, firing a dense and heavy dart of either DU or tungsten, and it strikes at I don't even know how many thousands of FPS. You will have what, maybe a twenty pound penetrator striking at maybe 4000 fps, impacting on a surface of only one or two square inches. This round will smash through the steel surface of the armor like a hammer through drywall. The bulk of the energy is going to be expended in destroying the armor, destroying the projectile, displacing other materials, converted into shock, etc. A whole lot of energy will be converted to heat as a secondary effect, that heat is going to be mostly generated by the energetic deforming of the metal, just as a nail or screw heats up when pounded or driven through a board. When you drive a nail into a board, isn't all of that energy used up just pushing the nail through the board? It's mostly used bending the wood. A lot of it is used to work through the friction. All of the work against friction is converted to heat.

Velocity is more important than mass for this function. High velocity is what makes it work. This is what KE is all about. This is why high velocity and high mass rounds act so differently in tissue. Where a .223 round and a good frangible round will literally vaporize a prairie dog, a 45-70 won't.
 
We are thankful you did not get hurt.You could put your eye out!!(you do were eye protection,don't you?)
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Thank you, until now I've never been too concerned with eye protection. I will be wearing my Winchester Glasses from now on though.
 
OK, let's do some Jethro Bodine Cipherin'

I found a KE calculator here: http://www.csgnetwork.com/kineticenergycalc.html

The .243, 55gr bullet is (rounding) .00356394 Kilograms. 3100 FPS is about 945 M/S.

This means the .243 has 1591.34 Joules of KE.

The .30-06, 147 gr is (rounding) .009525439 Kilograms, and 2400 FPS is about 731 M/S.

This means the .30-06 has 2545 Joules of energy.

Working backwards, to have the same KE as the .30-06, the .243 would need to hit the target at 3920 FPS.

Still not making sense.
 
I hadn't meant to start an complete thread on KE. It's bound to draw arguments.

Here it is, as I can best explain it.

Kinetic energy is not like any of the other measures of energy. They are really very different.

To calculate KE, kinetic energy, you need to have the velocity of the bullet, and the mass of the bullet.

Ek = ½ mv2

The most important thing is that your velocity, in doing this calcuation, is squared. Every step of 100 is increased to 10,000. and then halved. Your mass is only multiplied. When you add 100 fps of velocity, the result is expanded to 10,000. and divided by half. That is a big boost when you calculate KE. even doubling your bullet weight doesn't have that effect.

take these figures.

.243, 55gr (.0036 kg), 3,000 fps. This is .0036 kg, 945 mps, and 1505 joules.

If we double the weight, the energy in joules is doubled. with .0072 kg bullet the KE only is doubled to 3010 joules.

If we double the velocity, though, to 6,000 fps (1828 mps) Our KE goes up exponentially, to 6,000 joules. about four times the energy by only doubling the velocity.

we only have to increase the velocity by 1,200 fps to 4,200 fps (1280 mps) to double the amount of energy in joules (3010)

I know that is a lot to swallow. It took me a long time to put that together, it's been too long since physics class.

The reason your 30-06/243 comparison is so odd is that your .243 and 30-06 are working from two different angles. Your 30-06 is a heavy (147 gr) bullet at low velocity. it is nearly three times as heavy as your .243, and slower. when you increased the .243 to give a matching energy level, you only had to increase the velocity by about 1/3, or 800 fps.

The Ke, with the exponential increase, gives a distorted picture of what a rifle or pistol really does. The .243 in fact fires a 55 gr bullet at over 4,00 fps, with 2,700 joules of energy. The 30-06, at 150 grains, is actually weaker in terms of kinetic energy, at only 2,500.

Truly, the 30-06 has a bullet of 150 at 2,900 fps and 2,800 joules.

a low weight, high velocity round, the 55 grain .243, is nearly equal to the heavy weight, low velocity round, the 30-06. This load in a .243 is not at all like the 30-06 round, but they are equal in KE. other measures would show the 30-06 as clearly superior, since velocity will not be the deciding factor.

I hope this helped you out.

And as I said before, KE is going to be a greater factor in destroying the target it hits, by crushing and destroying the material. This .243 will literally explode when it hits steel. The 30-06 will probably be destroyed, but more energy is going to passed on to the target, and less energy will be wasted in destroying the projectile and the metal of the target.
 
Hi Mo, Glad you are OK.
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Before we got too far into physics lessons, this is certainly the most important factor.

What I am having a hard time wrapping my head around is that even with the higher velocity, the .243 still has ~40% less KE at 100 yards, yet does substantially more damage to the steel.

The velocities I used were output from JBM, the range was from a laser rangefinder.

I wonder if the smaller area the energy is spread across is a factor?

Using metric just to keep things in numbers larger than 1, the .243 bullet radius is ~3mm, so the frontal area would be ~28.3 sq mm, and the .30 cal is ~3.81mm so the frontal area would be ~45.6 sq mm

So at 100 yards, the .30-06 has 2545 Joules spread across 45.6 sq mm works out to ~55.8 J/sq mm.

The .243 has 1591 Joules across 28.3 sq mm is ~56.2, so more than the .30-06, but just barely.

This .243 will literally explode when it hits steel. The 30-06 will probably be destroyed, but more energy is going to passed on to the target, and less energy will be wasted in destroying the projectile and the metal of the target.
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I suspect this is a big factor. The Blitzking is designed for extremely rapid expansion, and it does that exceptionally well.
 
you are missing the most important part of the thing. You have two ways of measuring energy.

Kinetic energy favors velocity. Your huge velocity is what causes the explosion and destruction of material. The point, and so forth, also cause the destructive nature of the high velocity round. The energy contained in that .243, cranked up to 100,000 FPS, could literally blow a house apart when that energy is released. It would have the energy of dynamite. at near light speed, it could probably destroy a small asteroid. You would be amazed what a meteorite the size of a pebble can do. it will flame out so brightly that it can be seen from earth, all because of the enormous speed that it reaches.


Let's recalculate those numbers in a manner that doesn't favor speed, and instead, favors weight. Velocity is a destructive force, weight is more involved in pushing.

When we take the numbers and simply multiply, we get a number that favors weight.

The.243, at 00.36 KG, at 945 MPS, turns out 3.40 meters-kilograms of energy.

The 30-06 at .0097 kg, at 731 meters per second, turns out 7.10 meters-kilograms of energy

.243 = 3.40 of "push."

30-06 = 7.10 of "push."

With this new way of counting the "energy," we find that the 30-06 is over twice as powerful in the measurement that favors knocking the steel plate over. The 30-06 doesn't even compare to the .243 when we calculate the energy in a manner that favors destructive force. This is exactly what these two very different cartridges are. the .243 with the 55 grain bullet is intended to be a varmint gun, meant to blow small animals to kingdom come. The 30-06 is intended to punch long, bleeding holes in big game, rather than disintegrate their innards.

You know about roy weatherby, right?

Roy felt that velocity was the greatest factor in killing. He created an entirely new range of cartridges that were designed to be the fastest rounds in the nation. He was looking for one thing.

"I intend to create a rifle and cartridge that is certain to create such a shock when it strikes game that it will be as violent as being struck by lightning, and will thrown the animal to the ground, dead on impact."
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This is not exactly what he said, it is the best I can do, using his words as I remember them.

James howe created rifles and loads that could exceed 5,000 fps. He realized that they had no purpose in hunting, as they would have struck literally like explosives.

in this time, energy is only measured in KE. People like seeing huge numbers of KE. We, as shooters, must use our own instincts to realize whether one cartridge or another is proper to the use we intend for it. Do we want a cartridge, for example, that will dig a huge crater in a steel silhouette and simply knock it over, or do we want a round that will "push" that steel chicken 25 feet?

when I fired silhouettes, this is about what I found. A 22-250 blew a dime sized hole in the chicken, and pretty much just tossed it a few feet. The larger, heavier rounds might throw it 20 feet or so, leaving a smear of lead and a dent.

So that is it. One cartridge functions as a destructive device, and gets a high score as a destructive device. The other functions as a hammer, and gets a high score as a hammer.

Hope this helps. I understand if it's still unclear. This is college level physics, (maybe high school) and every day, thousands of people struggle with it.
 
I get on the forums to get away from math don't ya know?
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Think about the headaches I gave myself putting those together. Literally hours. Used to be simple, now, it takes a little more effort. About ten years ago, the math stopped working. Now it takes forever just to do simple things like that.:(
 
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