What About Foot Pound Energy

[eliduc]

I recently was given a box of federal 357 mag jacketed lead bullets. The box says 495 energy foot pounds at 25 yards and 1190 fps velocity. It seems that the bullet accelerates from zero and reaches peak velocity either inside the barrel or at the muzzel (MV is 1240) Then as it loses velocity over range the EFP gradually decreases until it reaches zero again as the bullet comes to rest. My question is, what consideration is given to the area of the point of empact of the traveling mass on the stationary object it collides with? It would seem that the wider the nose area of the bullet the kinetic energy would be distributed over a wider area of the object it collides with. Am I correct in concluding that the shock a bullet provides is related not only to the velocity and mass of the bullet but also to the size of the area of impact. (Not taking into consideration that bullets are designed to cause mechanical damage as well.) When a bullet mushrooms upon impact the kinetic energy of the bullet is distributed over a wider area. The bullet has less penetration over a wider area and more shock value than a pointed bullet that retains it's kinetic energy as it passes through an object. Does a lead wadcutter have more shock value than a lead round point of the same weight and velocity?

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[PaulB47]

Am I correct in concluding that the shock a bullet provides is related not only to the velocity and mass of the bullet but also to the size of the area of impact.

Sure. That is why kinetic energy is such a lousy measure of effectiveness; I don't know why manufacturers quote it. Most writers think momentum is a better measure of effectiveness. The old TKO uses momentum times bullet diameter, IIRC, probably a better measure yet, although it does not take into account differences between expanding vs non-expanding bullets, nor differences between round nose and flat nose.

Just ignore energy, it is BS. The best measure is direct comparisons, using gel, and even that method has lots of problems.

The good news is that bullets are a heck of a lot better than they used to be. "Don't worry, be happy."

 

[tac]

Yup, this energy thing can be a hoot to try and latch on to.

Example - let's take deer-stalking, as deer hunting is called here in yUK. The legal requirements are that the rifle used should produce a minimum of 1750 ft lbs of energy and 2450 fps at the muzzle, and be of a calibre no less than .240 ins (6mm).

That's not too bad, right?

Well, no, it IS bad, because that means that I can't use my .45-70Govt rifle to kill the full-size deer, or even the teeny stuff. That humungous BUFFALO-slayer is just TOO darn slow.

Same goes for EVERY black powder rifle ever made...

tac

 

[Koda]

My question is, what consideration is given to the area of the point of empact of the traveling mass on the stationary object it collides with? It would seem that the wider the nose area of the bullet the kinetic energy would be distributed over a wider area of the object it collides with. Am I correct in concluding that the shock a bullet provides is related not only to the velocity and mass of the bullet but also to the size of the area of impact.

if I understand you correctly, you are correct and 'they' do give the nose of the bullet consideration... I think its called the "meplat". On low energy (ralatively speaking) pistol rounds that are also used for hunting they usually give them a flat nose from a hard cast lead bullet to literally punch thru hard bone... like the skull of a bear.
here is an example: 10mm 200gr Hardcast Solid™ 50rds.

as fas as the .357 round you mentioned 495 fl/lbs seems pretty light for a hunting round so I might be off on what your asking...

 

[Jamie6.5]

The kinetic energy as advertised in ballistics is strictly based on the classic physics formula relying on Mass x Acceleration.
What effect the cross section of the bullet's meplat has in delivering that energy early in the impact/penetration scenario is something often overlooked. Except by writers and enthusiasts like Elmer Kieth.
If you follow the theory of damage done by delivering shock to the CNS and circulatory system, arguing against large(r) meplat bullets becomes futile.

The argument against them always centers around ballistic coefficient and the amount of velocity they can retain downrange.
So like much of exterior ballistics and killing power, it comes down to a tradeoff between range and effectiveness.

But if you really want to see how effective large meplat bullets can be, load them up in something that will really push them.
Like a 158gr .357 Mag bullet in a .35 Whelen cartridge leaving the muzzle at 2500+fps. The reaction of things that get hit with them is amazing!

 

[tac]

You'd really be surprised to see the antics of people trying to get out of the way of the piddling 9mmP bullet..........

tac

 

[Riot]

My question is, what consideration is given to the area of the point of empact of the traveling mass on the stationary object it collides with? It would seem that the wider the nose area of the bullet the kinetic energy would be distributed over a wider area of the object it collides with. Am I correct in concluding that the shock a bullet provides is related not only to the velocity and mass of the bullet but also to the size of the area of impact. (Not taking into consideration that bullets are designed to cause mechanical damage as well.) When a bullet mushrooms upon impact the kinetic energy of the bullet is distributed over a wider area. The bullet has less penetration over a wider area and more shock value than a pointed bullet that retains it's kinetic energy as it passes through an object. Does a lead wadcutter have more shock value than a lead round point of the same weight and velocity?

Lots of factors determine how the bullet energy is dispersed into the target.

*Trajectory Angle
*Hardness of the target
*Weight distribution in the bullet (if the weight is more in the back of the bullet versus the front or middle)

A 56gr bullet travelling at 1100 FPS going through your shoulder may have less pressure exhibited on a target than a 45gr bullet traveling at 900FPS that hit your femur bone.

Speed, size, grain...that's all fine and dandy...FMJ, JHP, SP, BT...all these bullets exhibit different penetration, fragmentation and expansion...the main goal here is hitting the target in the most effective area, regardless of the bullet type (hence why most of the 9mm v. 45ACP argument is a moot point).

 

[The Heretic]

Energy is a factor, "shock" is irrelevant.

What counts is the "work" or damage done to what you are hitting with the projectile. The work will depend on the energy, mass, velocity and design of the projectile - especially the design of the projectile.

The projectile has to penetrate far enough to "work" (do damage to) on important tissues, especially organs and/or strike and damage the central nervous system. A .223" 62 grain projectile at 2800 fps that expands and penetrates to 12 to 18" will be as lethal as a .429" (.44) 240 grain projectile at 1000 fps that expands also and penetrates the same distance. I've seen .223" projectiles expand to .6" or more.

If a projectile can penetrate to a vital organ and has enough energy and velocity to do the work, it will be effective.

Much more important is bullet placement.

A couple of weeks ago I was watching a dozen or more bison hunting vids to convince myself to buy a .45-70 rifle (I did). The most effective shot I saw was someone who shot a large bull bison from about 75 yards with a .30-30; he put it down instantly with one shot. Bang - the bison bull collapsed on the spot, as soon as it was shot (skip to the 3 minute mark):

All the other shots I saw, with .45-70, .30-06, .500 magnum, either took multiple shots or several minutes for the bison to go down.

A flat point on a large diameter projectile is somewhat better than a rounded point, assuming both do not expand, but if they do expand, then diameter doesn't matter than much. A .22 diameter hole in a person is not that much smaller than a .45 diameter hole. It is all about the damage done, and that is done either by expansion or tumbling, and expansion is better - assuming the projectile penetrates to or through vital tissues.

 

[tac]

Now THAT's going to sting.

tac

 

[The Heretic]

But if you really want to see how effective large meplat bullets can be, load them up in something that will really push them.
Like a 158gr .357 Mag bullet in a .35 Whelen cartridge leaving the muzzle at 2500+fps. The reaction of things that get hit with them is amazing!

The problem is that a projectile designed to expand at 800 to 1500 fps, may explode at 2500 fps. I have seen gel tests where a given expanding 9mm projectile will penetrate less the faster you drive it - in the example I saw, it was the difference between a subsonic load and a super sonic load, both shooting from the same gun, same gel, same projectile - 50 to 100 fps faster the projectile expanded sooner and penetrated less.

 

[The Heretic]

In short, pick the right load, practice with a similar load (FMJ/et. al. is okay for practice as long as it is the same recoil, same weight, hits the same place on the target), become proficient and confident with the firearm at the distance you are shooting, and then hit the target at the right spot.

A hit with a .22 rimfire is better than a miss with a .44 magnum.

The right load matters. You don't want to shoot a big moose with a high velocity .357 110 grain load, and you probably don't want to be shooting squirrels with a .44 magnum bear load. The right projectile weight, projectile design for the target and velocity, and bullet placement will make all the difference.

 

[Jamie6.5]

The problem is that a projectile designed to expand at 800 to 1500 fps, may explode at 2500 fps. I have seen gel tests where a given expanding 9mm projectile will penetrate less the faster you drive it - in the example I saw, it was the difference between a subsonic load and a super sonic load, both shooting from the same gun, same gel, same projectile - 50 to 100 fps faster the projectile expanded sooner and penetrated less.

1st off, 9mm slugs are not .357 slugs.
But, all 158 gr .357 slugs aren't created equal either.
A well constructed .357 bullet, with a large meplat is required to get the results I've seen, and it wasn't a matter of them coming apart too early.
The only things coming apart were the targets.

Except the ones that were turned instantly to mush. But those were fun too.

 

[The Heretic]

1st off, 9mm slugs are not .357 slugs.

No - they are .355" projectiles - a whopping .002 to .003" difference!

And the velocity of the 9x19 vs .357 mag, with the same weight projectile of the same design, in the same size handgun (semi-autos have a longer barrel than a revolver of the same length), below 140 grains or so is very close. The .357 magnum does much better with heavier projectiles above 150 grains, and is better for hunting medium to large game for that reason.

That said, there was the guide in Alaska who took down a charging brown bear with a compact (single stack) 9mm semi-auto.

 

[Jamie6.5]

No - they are .355" projectiles - a whopping .002 to .003" difference!

Gee, do you REALLY think the .002" is the only difference in how they're constructed?
Silly you.

 

[The Heretic]

Gee, do you REALLY think the .002" is the only difference in how they're constructed?
Silly you.

The construction of any projectile depends on the intended usage. You can get 9x19 ammo with very similar or the same projectiles (minus a little bit of diameter) as .357 magnum if you look for it.

My point was that for a given sized handgun, within the constraints of the 9x19 cartridge (does not do well with projectiles above 140 grains), it is almost as effective as the .357 magnum which is considered to be a good "man stopper".

I personally would not have been carrying a 9mm compact semi-auto as a backup bear gun in Alaska - I always carried a .44 magnum when I worked there. But I do carry a 9mm semi-auto for personal protection against humans and leave the big boomers at home.

I have most caliber handguns and rifles from .22 RF up to .460 mag and .50 BMG, so I can pretty much choose whatever is appropriate for the task. But projectile design and bullet placement are the two most important factors whether I am choosing something for self-defense or hunting.

If I were hunting "thick skinned" and/or heavily boned dangerous game like elephant or cape buff, I would maybe chose a heavy non-expanding projectile at a decent velocity as the first shot, and something expanding but heavily constructed to penetrate as the second shot. From a rifle I would probably have a RN or spire point, and not a flat point. Penetration would be key in those cases.

For bear, I carried a thick jacketed SP 300 grain (Barnes JSP) 1300 fps load in my DW .44 mag in Alaska. My goal again was penetration from any angle. I wasn't hunting bear, I was just carrying for bear protection, so the shots would have been to stop a charge by first breaking the front shoulder and then the rear hips if still coming at me. A heart or lung shot might be eventually lethal, but I would want to stop its means of locomotion if it was charging me.

 

[No_Regerts]

If you want an example of how energy means less than you'd think, look at arrows. Arrows have extremely high sectional density and very little energy. The damage caused to vital organs is devistating. People argue about the difference between how arrows cut vs how bullets do their damage, but opening holes and disrupting the central nervous system works either way.

 

[The Heretic]

If you want an example of how energy means less than you'd think, look at arrows. Arrows have extremely high sectional density and very little energy. The damage caused to vital organs is devistating. People argue about the difference between how arrows cut vs how bullets do their damage, but opening holes and disrupting the central nervous system works either way.

Good points, and it is the damage done to tissue that stops any animal, not the energy. The energy and velocity facilitates the work though.

 

[PaulB47]

The kinetic energy as advertised in ballistics is strictly based on the classic physics formula relying on Mass x Acceleration.

Actually, the formula for kinetic energy is 1/2 mass times the velocity squared. Keep in mind that kilograms are a measure of mass, but pounds are a measure of force! I think the measure of mass in English units is something like slugs, but only a madman uses English units while doing physics calculations.

The Mass X Acceleration that you mention is force, not energy.

The energy and velocity facilitates the work though.

I think it's more accurate to say that impact velocity, mass and bullet construction does the work. Clearly it matters what type of bullet you are using. As to energy, it's just a number derived from mass and velocity, and not of any particular utility in terminal ballistics. One might as well use momentum (mass times velocity) as I said before.

 

[The Heretic]

I think it's more accurate to say that impact velocity, mass and bullet construction does the work. Clearly it matters what type of bullet you are using. As to energy, it's just a number derived from mass and velocity, and not of any particular utility in terminal ballistics. One might as well use momentum (mass times velocity) as I said before.

Projectile construction could be said to maybe provide leverage - although I would assert that this would be stretching the definition a bit.

Work = Force * Distance

Force = Mass * Acceleration

 

[The Heretic]

A decent treatise on this subject:

Bullet Penetration - Duncan McPherson
Modeling the Dynamics and the Incapacitation Resulting from Wound Trauma

It's been over a decade since I read it, but it seemed like the right approach to the subject