Home Forums Hunting & Shooting Hunting Rifles Stupid energy question #4362

All things being equal (even though I know they're not), would a 100 grain bullet impacting a target at 1000 ft/lbs have the same effect as a 200 grain bullet impacting at 500 ft/lbs?

Energy is "cute",but velocity is what makes a bullet act on something.

Retained velocity interests me more than energy................

Energy is just a Number.

The Wound Channel is the only thing that matters.

Whether a 200 grain bullet with only 500 ft pounds left will make much of a wound channel depends upon the animal and the bullet construction. The Wound channel needs to be deep enough to cause damage to vital organs.

Hard Cast bullets go deep even if they are moving slow.

Hard Expanding bullets (Triple shocks, fail safes, etc) need a higher impact velocity to do the damage.

Stick gets his wound channel by using x bullets at high impact velocity (or my using varmint bullets at REALLY high impact velocity). The high velocity and higher level of skill let Stick deal death from a different ZIP code.

Lots a guys get big wound channels by using hard cast lead big bore bullets at lower velocity. They like to get up close and personal.

There's many ways to skin a cat,

How you choose to do it is up to you . . . . . .

BMT

Energy is the potential to do work, but the work does the bullet. The work you want is a wound channel of a certain dia and length.

Bullet construction has the greatest effect on terminal performance, and unfortunately there are no easy numbers or ways of measuring how well a bullet will perform based on some given number. Attempts have been made to correlate energy and sectional density, but really don't hold.

In the real world what I'd say matters for a high powered rifle is a bullet that is constructed so that it will consistantly exit on broadside shots at all impact velocities, and be going at least 2000 fps on impact. If you hold to that criteria, and hold where you need to, results are certain within whatever range you can keep those bullets impacting at 2000 and above.

Kinetic energy increases with the square of the increase in the speed of the body.

Kinetic energy increases with the square of the increase in the speed of the body.

The lighter bullet at twice the speed has 4 times the energy.
The 100 grain bullet at 1,000 fps has twice the energy of the 200 grain bullet at 500 fps.

read the original post, it stated impacting at given ft/lbs, not fps.

It is still meaningless w/o knowing the bullets construction. If the 100 gr bullet was 35 caliber and lightly constructed, it would behave entirely different than say a stoutly constructed 25 caliber.

Same with the 200 grainer, need to know caliber and bullet construction. That 200 grainer could bore straight through, or barely make it in depending on caliber and construction.

The answer is still, NO, they effect is not the same.

I can tell you that a 200 grain .308 bullet impacting at 500 fps from a .300 Whisper will completely penetrate a deer and kill it in its tracks.

Have dabbled with a 1-8" Whisper tossing 240SMK's.

I'm FAR from impressed on terminal affects. It's akin to a fieldpoint,which isn't the pinnacle of Archery aspirations,let alone close.

Would take both over an atlatl,but they is all bottom rung implements.......................

The whisper in subsonic mode is a headshot only proposition. Now load it with 125 gr btips and drive them around 2000 fps and you can put it in the heart/lungs.

And if you ignore bullet construction, the original question cannot be answered. The 200 gr @ 500 ft/pounds if properly constructed will perform better than the 100 gr @ 1000 ft/pds if improperly constructed.

As stated, energy is the capacity to do work. Both energy and work have precise definitions.

On impact, the energy of the bullet is transformed in three ways: 1) crushing and breaking tissue, 2) elastically stretching tissue (which is bruised, but not crushed), and 3) deformation and disassembly of the bullet. The way the energy gets divided depends considerably on whether you have a low mass, high speed projectile, or a high mass, low speed projectile. It also depends considerably on bullet construction.

You often hear people say "energy never killed a deer". That is absurdly wrong. It is precisely the kinetic energy of the bullet that creates the wound channel, and the wound channel kills the animal. However, you can't tell how effective (i.e., how the energy will be divided) a bullet is going to be on impact just from the KE. You have to know a lot more.

Sure - that's why all the sub-atomic particles that go whizzing through us at nearly the speed of light all kill us stone dead. Been killed untold times just in the last hour...

What about momentum-
Velocity (not squared) times the mass equals momentum,
I know some writers have made a case for momentum being more important in "killing power" than kinetic energy.
However,I like the late Finn Aagards saying-'life is a complicated force that cannot be expressed in terms of x, y, and z'-okay that was probably a paraphrase on my part! <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

Energy is ft-lbs not ft/lbs. I think I know what the question is but you asked it poorly enough to get all kinds of responses.

Some like to use momentum rather than energy to determine a rounds effectiveness because energy is not a linear expression of the dynamic event. In other words, an earthquake has energy, as does sunlight; energy obviously can act in any direction. Energy is what throws a animals insides around and upsets a bullet. Energy can change forms like creating the thump sound when you hit something. It is not the best mathamatical expression for what makes a bullet penetrate, that's momentum.

So, the 200 grainer is more likely to penetrate due to its larger mass and the 100 grainer is more likely to throw innards radially.

All of this is why high velocity bullets need to be tougher for assured penetration and large mass bullets need to be designed to expand at lower energies or hit bone. Both are effective but do represent two different ways of getting the job done.

Bend over bare assed at 100yds and we'll see if the 100X outta the 257Wby leaves a mark.

I've a hunch,the impression would be audible,visual and tangible,but am ready for any corrections you might could espouse..........................

IMHO,CNS pokes aren't much of a trauma indicator,as the requirements aren't too demanding of the projectile or it's velocity.

For conversation a .338" 200gr projectile with a BC of .450(Speer-ish designator),makes 500ft lbs at 1060fps impact velocity.

A .257" 100gr projectile with a BC of .420(XLC-ish designator),makes 1000ft lbs at 2135fps impact velocity.

having shot both diameters,both near and far,I'd fight tooth and nail for the 2000fps+ impact,over the 1000fps arrival.

Runs hand in hand,with my not being much in the way of impressed with a Whisper launched 240SMK at subsonic speeds/impacts.

Velocity on scene,do tell the tale.........................

OK you damned bunch of Einsteins. It's all chicken but the bone....

Things ain't equal...therein lies the rub.....................

If I'd knowed that huntin' required so much arithmetic, I don't think I would have enjoyed it so much for the past fifty years.

Can you tell the difference between a 22lr and a 22-250?

That'd be velocity and math ain't required..................