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Old August 21, 2011, 05:14 PM   #1
300blackout
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Interesting 'knockdown' power article...

Hi-

Thought I'd share this. I found it very interesting, particularly these two parts:

Thanks to the human races' continued proclivity towards killing off parts of itself, we know that foot-pounds of energy is a myopic way of describing projectile effectiveness. How much kinetic energy does it take to stick a knife or spear between the ribs of a game animal?

The relatively modern broadhead arrow, with less KE than a .22 Short (50 fpe) has been used to kill all species of game. As Dr. Fackler wrote in 1987, "It is difficult to be optimistic for the future when these weapons developers still use the scientifically discredited "kinetic energy deposit" method to estimate wounding effects."


http://www.chuckhawks.com/energy_transfer.htm

Comments?
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Old August 21, 2011, 06:26 PM   #2
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Thanks, that was a very interesting article. I feel that we have become so obsessed with kinetic energy and fps that we sometimes forget that when hunting we are trying to kill something and not just hit it. Hunting is very different from target shooting and putting animals down humanely is important.
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Old August 21, 2011, 08:17 PM   #3
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I've always thought that those various made-up "power factors" and "TKO values" are a bit silly.

I wonder if the author considered momentum at all. I whipped up a quick graph, and the results don't look too bad compared to the wound profiles. It's not a perfect correlation, but it's not bad.
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Old August 21, 2011, 08:26 PM   #4
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People have been trying to quantify projectile effectiveness for centuries. Different biases (heavy bullet vs high velocity, large caliber vs shape factors, etc) yield different results, and leave us no closer to a reliable indicator of effectiveness than before we started.

As so eloquently put by Ben Franklin, "figures don't lie, but liars can figure".
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Old August 21, 2011, 08:43 PM   #5
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Only thing that matters in the world of bullets is how much tissue can be disrupted. That's It.

energy, sectional denisty, etc, etc are just factors of explanation and should not be taken as sole determining factors to what a bullet can do, because in ballistics there are diminishing returns and instances in which one or more factors must be modified to make up for the loss of another.
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Old August 21, 2011, 09:20 PM   #6
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Quote:
Originally Posted by kozak6
I wonder if the author considered momentum at all. I whipped up a quick graph, and the results don't look too bad compared to the wound profiles. It's not a perfect correlation, but it's not bad.
Well, the ultimate in high momentum/low energy projectiles would be a bowling ball, which certainly works well for sending bowling pins flying while doing almost no damage to them.
I you were to throw a bowling ball at a deer, it might knock the deer off its feet and perhaps leave a large bruise but it would be very unlikely to kill it.
Momentum, by itself, does not tell the whole story either.
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Old August 22, 2011, 10:04 AM   #7
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Anybody that lives in a shotgun only area knows this already. Do we really need to spend more money on nonsense like this? I did land clearing/logging for a couple of years in shotgun areas and the thickets were loaded with dead deer after shotgun season. Now, the newer copper slugs are all higher velocity but that is not what makes them so effective. Most of the new slugs are designed to fragment and cut. This guy keeps referring to spears and arrows, which have nothing to do with bullets. Arrows and spears are designed to cut. I have been bow hunting for a long time and believe me, that crowd has its own issues with penetration with out involving them in the bullet mess. I would have to say this guy does not know what he is talking about. He tries to cut out all variables unless they side in his favor. Anybody remember the advertisement with the huge block of butter that stopped the (I think 30.06) bullet and the arrow went all the way through? If you gut shot a deer with an arrow, a 30.30, or a 30.06, which deer would be more likely to be recovered? What the heck, add a 220 swift to that.

Last edited by Gunplummer; August 22, 2011 at 10:06 AM. Reason: missing word
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Old August 22, 2011, 10:16 AM   #8
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Quote:
I would have to say this guy does not know what he is talking about. He tries to cut out all variables unless they side in his favor.
Exactly Chuck Hawks is NOT a reliable source of information. His "articles" are full of brand bias and other such nonsence.

The fact that he is willing to put up articles written by "anonymous" should be enough to show how full of **** he is.
That same article has a section discounting all 147 grain 9mm ammo without stating any facts. This person says they "suck" are "weak", a "fad" but never offers any factual information to support such a claim.
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Old August 22, 2011, 01:32 PM   #9
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A good example of how Kenetic Energy is not a good measure of performance is comparing a 22-250 with 50gr bullets and a 45-70 wiith 405gr bullets. The charts show that the 22-250 has the edge at the muzzle and are virtually the same at 100yds but which had you rather have to stop a charging bear???

Perhaps Kenetic Energy can be used to measure differences in two similar cartridges shooting bullets relatively close in weight but even that is iffy. I feel that bullet construction has way more to do with killing power than KE does. A good example is shooting animals with FMJ's then shooting them with Soft Point bullets. The bullets ability to expand well but not over-expand is paramount to transferring energy and tissue damage IMHO anyway.
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Old August 22, 2011, 01:49 PM   #10
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KE is just a form of shorthand for people who understand which cartridges go with which game animal and who also have a little knowledge about which bullet meets their need.

Don't blame KE because some people oversimplify and misuse it.

Now, give me a 16-pound bowling ball and a suitably-sized trebuchet and we'll see if the deer gets up from a head shot. Or maybe 9 duckpin balls would be better; sort of like using buck shot.
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Old August 22, 2011, 02:46 PM   #11
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Yeah, I got a comment, 300! Chuck Hawks, whoever that
really is, is an IDIOT!
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Old August 22, 2011, 04:04 PM   #12
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Gunwriters are shills for the industry. Industry wants to sell the latest and greatest. You can really pump something based on KE because KE is Mass times Velocity squared. Just increase the velocity by 10 and KE increases by 100.

It is a lot harder to increase the Momentum of something by ten. Momentum being mass times velocity.

By the way, only momentum is conserved, KE is not.

For decades gunwriters have filled canyons full paper on the difference between a 270 and 308, (about .031" ) KE spreads the shilling distance out to a respectable level.

Hey, who needs to aim, if you have enough velocity you can down big game regardless of where you hit them.

Don't worry, it is a Weatherby!

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Old August 22, 2011, 04:12 PM   #13
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momentum is a very important factor. Its surprising that when comparing two loads one seems to have the advantage with kinetic energy using its lighter bullet and high velocity, but the heavier, slower load has the advantage in momentum.

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Old August 22, 2011, 04:35 PM   #14
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Slamfire
Quote:
You can really pump something based on KE because KE is Mass times Velocity squared. Just increase the velocity by 10 and KE increases by 100.
You need to work on your math a bit. If you increase velocity by 10 percent the energy goes up by 21.1 percent, not a 100 percent.
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Old August 22, 2011, 05:00 PM   #15
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Actually, both momentum AND energy are conserved in a bullet strike. And it is that fact that makes properly constructed high-speed bullets so deadly.

In elastic collisions (both objects bounce off each other), this is obvious.
In inelastic collisions (object #1 gets embedded in object #2 and both take off together), not so obvious -- but still true.

EXAMPLE:

A 185gr bullet fired out of a 308Win smacks into an 11-lb woodchuck with an impact velocity of 2,420fps and doesn't exit. (Let your imagination run wild here.)

Conservation of MOMENTUM says that chuck takes off backwards at 5.6fps until it hits the ground in a bloody pile (trust me on the math).
~~~~~~~~
Conservation of ENERGY says that the bullet had 2,407 ft-bs of energy when it hit the chuck, and somehow the chuck's velocity only accounted for 5-1/2 ft-lbs of that energy. Somehow we "lost" 99.8% of the bullet's energy, right?

Wrong.

That 2,402 ft-lbs of missing energy all wound up inside the chuck -- heating its guts to boiling along the bullet (and fragment) paths, and throwing those guts in all directions inside it until it hit the ground like a hide-filled strawberry milkshake.

Energy is never lost. It just takes different forms.
And neither you nor I want 2,400 ft-lbs of energy running loose in our guts.
Mexican food is bad enough.

Last edited by mehavey; August 22, 2011 at 07:20 PM.
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Old August 22, 2011, 06:00 PM   #16
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Well I love these "energy" discussions almost as much as I love the "knock down power" discussions. Modern hunting arrows don't kill by impact, they kill by cutting and loss of blood.

With rifle, today everybody seems to be on the magnum craze. I laugh when I read about guys punishing themselves with a 375 H&H in the lower 48 as they may happen upon a bear.

I've yet to worry about any animal with a 30-06 and no I wouldn't worry with a 270 Winchester either. Love to hear guys talking bout those big ole dangerous boars. I won't do it but guys down here hunt them with dogs and a knife.

Maybe I'm showing my age but as a kid my grandfather, uncles, there friends hunted everything with a 30-06 or a 30-30. Certainly there was the occasional 270. One neighbor with money had a real fancy Weatherby, IIRC he had a pretty good flinch to go with it. But he killed a fair amount of deer with it and no bears, unlike my great uncle who had no problem killing a big Canadian black bear with one shot from his 30-06. Talk about enegrgy and knock down power is fun to waste time over beers with. But proven performers get the job done when needed.
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Old August 22, 2011, 07:28 PM   #17
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Quote:
Originally Posted by mehavey
That 2,402 ft-lbs of missing energy all wound up in the chuck -- heating its guts to boiling along the bullet (and fragment) paths, and throwing those guts in all directions inside it until it hit the ground like a hide-filled strawberry milkshake.

Energy is never lost. It just takes different forms.
And neither you nor I want 2,400 ft-lbs of energy running loose in our guts.
In stopping that bullet, the woodchuck converted the 2400 ft-lb of kinetic energy into about 3 BTU of heat.

1 BTU = 778 ft-lb

Since a BTU of heat is defined as the amount of heat needed to raise the temperature of one pound of water by 1 degree F, 3 BTU of heat would raise the body temperature of the 11 pound chuck about 0.27 degrees F, assuming that a chuck is mostly water.
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Old August 22, 2011, 08:08 PM   #18
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One pound of pure water (at sea level). I think Big Pard had it right. All the facts and figures go out the window when bullet construction is added in. It amazes me the way hunting bullets react in different media. The bullet manufacturers tested for years and spent millions figuring it all out, so I will go with what they say most of the time.
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Old August 22, 2011, 08:25 PM   #19
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3 BTU of heat would raise the body temperature of the 11 pound chuck about 0.27 degrees F, assuming that a chuck is mostly water.
But since heat transfer through water along the bullet (and fragment) path is so limited, let's say that only 1/10 of one percent of the Mr Chuck's fluids are exposed to the thermal energy transfer. That mean those bodily fluids immediately adjacent to the bullet's path rise approximately 247°F (which can't happen)

Just for grins, Assume the blood started at ~98°. That means the excess rise above 212° (133°) gets converted to steam... which is even worse for Mr Chuck.

"Dumping all its energy in the body cavity" is the name of the game for modern bullets. And properly constructed for design penetration depths/traveling at high-velocity rifle speeds, these V² killing machines act akin to Klingon disrupters. Past certain speeds, hydrocodes are needed -- then a bone strike turns neat performance models on their heads. It becomes very black magic.

Ask the combat surgeons.

Last edited by mehavey; August 22, 2011 at 08:38 PM.
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Old August 22, 2011, 08:37 PM   #20
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Quote:
Only thing that matters in the world of bullets is how much tissue can be disrupted. That's It.
If it's not the right tissue that's disrupted it doesn't matter much.

It's not just about how much tissue is disrupted. The particular tissue that's being disrupted is also critically important.
Quote:
Conservation of MOMENTUM says that chuck takes off backwards at 5.6fps until it hits the ground in a bloody pile (trust me on the math).
This is only true if both the objects in the "collision" are completely inelastic. In reality the woodchuck will deform in the collision and the bullet might depending on its construction. The force required to accomplish that deformation uses up energy and momentum.
Quote:
That 2,402 ft-lbs of missing energy all wound up inside the chuck...
Not quite. Some was dissipated as sound, some was probably dissipated deforming the bullet. And if the temporary cavity significantly exceeded the size of the chuck then some of it was used to spread woodchuck pieces over the countryside.
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Old August 22, 2011, 08:49 PM   #21
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...then some of it was used to spread woodchuck pieces over the countryside.
There you go again. Getting all technical on us.

One of my earliest memories of Hi-V bullet effects was when I was 8 years old on Cape Cod back in the early-mid 50s. My father & I used to go chuck hunting in/around the then-vacant WW-II barracks on a largely-deserted Otis AFB. At age 8 I looked askance at Dad's converted `06 Springfield, but I loved that 220 Swift.

I shot my first chuck out of the car window (it was the 50s, remember) w/ that Swift at about 40 yards. It did exactly as you described. It also had an effect on that 8-year old. I never forgot it -- ever.

I thought about that destruction again as I was listening to the carnage wrought by Hassan's FN Five-seven. No, it didn't "blow people apart," or blast them through plate glass windows. It merely destroyed everything within a 4-6" radius of its passage.

Last edited by mehavey; August 23, 2011 at 07:28 AM.
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Old August 29, 2011, 12:36 PM   #22
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That math is all too hard for me

I just remember 30-06, 165, M70

done.

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Old August 29, 2011, 12:49 PM   #23
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THplanes, slamfire never said "10%," he only said "10". It's obvious in context that he meant a factor of x10, which would raise KE x100 as he said.

So he might need to work on more explicit terms, and you might need to work on your inferences.
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Old August 29, 2011, 02:00 PM   #24
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In stopping that bullet, the woodchuck converted the 2400 ft-lb of kinetic energy into about 3 BTU of heat.

1 BTU = 778 ft-lb

Since a BTU of heat is defined as the amount of heat needed to raise the temperature of one pound of water by 1 degree F, 3 BTU of heat would raise the body temperature of the 11 pound chuck about 0.27 degrees F, assuming that a chuck is mostly water.

Oh boy, oh boy, now we get to add which round generates more BTU's.
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