Which is more important in ballistics?

Shot placement, penetration and wound diameter.

There are many ways to accomplish this. Velocity along with bullet weight will give a mathematical energy number. It is one way to predict penetration and expansion, but is not perfect. It doesnot take into consideration bullet construction.

I place more stock in ballistic geletian test results and actual street performance. The numbers are not useless though. If you know that load "A" is a proven performer, then you should be able to predict that a different chambering with similar bullets and energy numbers should perform about the same.
 
In my opinion bullet weight and the energy behind the bullet are the best factors when considering personal defence. However those can also have a significant impact on accuracy as well.

I saw a rifle on TV here a few days ago that shoots a 6.80 round which shares the "knock down" power of the 7.62 with the accuracy of the 5.56. Seems pretty cool, but I would guess it's really all a matter of personal opinion.

Sent from my LGL75C using Tapatalk 2
 
I can cite a good example of bullet failure. An acquaintance of mine took his 6" Colt Python on a hog hunt. His first shot was an easy broadside shot, maybe thirty to fifty yards. The boar was pretty big, around 350 lbs. His ammunition? Remington factory load .357 Magnum 125 gr. Semi-jacketed Hollow points. When hit, the porker turned and looked at the man, and another shot was fired, the pig ran, changing directions with each shot. This man emptied his Python, reloaded and fired three more shots before somebody put a 12 ga. slug into the boar and the animal "passed."

An autopsy revealed all nine perfectly expanded bullets just under the skin in the top layer of fat. None had penetrated to reach vital organs.
Click to expand...

Shooting a 350 lb hog has little to do with self defense from other bipeds.

While I agree that the 125 Grin JHP is a poor choice for hunting large dangerous game. I find it difficult to believe that the bullets expanded well and penetrated only skin deep. Factory loaded 125 grain 357 Magnum loads clock around 1600 FPS from a 6" revolver which is 711 FPE. The 125 Grain 357 Magnum was very prone to fragmentation at anything above 1400 fps.

I shot one hefty ground hog hitting just above the rectum and the bullet exited just under his chin, pulling most of his intestines out through the exit hole. This with a .44 Magnum using a 245 gr. Keith cast bullet.
Click to expand...

Just curious, what velocity was that 44 traveling at? I understand the penetration because I have been hunting with 44's for 30 years.
 
Nanuk, if hunting big game with a .44 you probably have not been using JHP.

I have seen a Remington 240 JHP fail tp penetrate the shoulder cartilage of a 200ish pound boar. The round in question was fired from a Marlin 94, and its velocity resulted in rapid expansion and poor penetration.

It isn't just velocity; it isn't just sectional density; it isn't just bullet construction. It is how all three work together that determine whether a load is a good choice for a given target type.
 
Velocity and energy...

They are related.

When it comes to handguns...

The mass of the projectile is important... and penetration.

Also momentum as mentioned is probably better as well...

Velocity and Mass

Momentum is--> p=mv

So a 9mm round that is 115gr and is traveling 1200fps... has a momentum of...

115gr*1200fps=138000grf/s (grain feet per second) (or 19.714 lbf/s)

a 230gr 45acp at 900fps = 207000grf/s (29.571lbf/s)

180gr 40sw at 1010ftps = 181800grf/s (25.971lbf/s)

Muzzle energy is really Kinetic energy... and is a different formula

Kinetic energy is--> E (sub k)=1/2mv^2 (.5 * m * v squared) (sub k... when written is like the opposite of the exponent in x^2 or x squared, so the k sits below the line rather than above... you could leave it out and just use "E" but it is improper)

A second calculation is needed to properly express the value in imperial/english units. And to turn the grains into the familiar pounds we see in the stats we are given... ft/lb (divide the amount from the above formula by the product of 32.163*7000... 7000gr per pound and gravitational constant of earth in fps... as pounds are not a measure of mass) This extra calculation is why the metric system is superior for this sort of thing... calculations of forces, energy, work... much easier.

(Also... some use 32.174 for the gravitational constant, it changes the numbers slightly, but not enough to really matter. 32.163 is the average local gravitational constant of the US and other areas similarly situated away from the equator. 32.174 is the standard gravitational constant global average and the one used for most computations outside of bullets. US manufactures tend to use the first. Use which you prefer.)

45acp example...

.5*230gr*900fps^2=93150000

divide above by 32.163*7000 (225141) = 413.74ftlb

Differences between momentum and Kinetic energy.

Momentum is directly proportional to velocity and mass. Double either velocity or the mass, and you double the momentum. Momentum also has a vector/direction.

Kinetic energy is directly proportional (or linear) to mass... double the mass means double the energy... but it is exponential to the velocity... double the velocity means 4 times the energy. Kinetic energy does not have a vector/direction.

A 1000lb car moving 1fps and a ball that is 1lb moving 1000fps both have the same momentum... but the ball has much much more kinetic energy

1000lbf/s momentum for both.

15.55ft/lb energy for the car, and 15547.26ft/lb for the ball

So how does all this fit together?

Momentum can be equated to how much time a given force takes to stop the object.

Kinetic energy can be equated to what distance a given force needs to stop the object.

An example using a car... braking distance is related to kinetic energy, and how long in seconds from first applying the brakes till complete stop is momentum.

Momentum is also related to inertia... which is an object's resistance to changes in its momentum or motion. Kinetic energy has no such direct association. Sure as momentum increases, so to does energy, but energy does not factor into inertia in that way.

Mass is also directly related to inertia... mass has inherent inertia, so more mass means more inertia... Mass and momentum team up when the force applied is opposite to direction of motion.

Energy must be conserved within a system...

Meaning momentum and kinetic energy both transfer to the target when hit. When its all said and done, the amount of energy and momentum of all the components involved combined must equal the input amounts.

What matters with bullets is the percentage of each transferred.

What about different bullets?

Rifle rounds and FMJ handgun rounds tend to pass straight through and transfer a small proportion of there energy and momentum.

Hollow points are designed to stop within the target or at least expend more energy before passing through.

For FMJ bullets, both rifle and handgun, the force trying to stop the bullet can be said to be constant. For hollow points, that force increases over time as they expand, up to the point of full expansion.

Energy/momentum transfer creates cavitation of the fluids (and by extension the tissue it is contained within) of the person/animal hit.

Now... since rifles have inherently more energy and momentum than handguns, if a rifle round only transfers 30% of its energy, that is a far greater amount than say 30% from a 9mm... Which is why rifle rounds create more cavitation in the body.

When cavitation exceeds the elasticity of the tissues of the body it passes through, it causes permanent damage beyond the path and width of the bullet... This is why rifles are more effective than handguns. Even hollow point rounds in pistol calibers create relatively little cavitation.

So any bullet that passes through a body must create enough cavitation as it passes through to be effective. (barring direct hits to vital structures)

More cavitation means more damage over a wider area.

Cavitation can be increased by adding drag, which is what hollow points do. Even flat nosed bullets increase drag.

So if we do not have sufficient cavitation to cause a lot of damage outside of the bullet path, we must rely on hitting vital structures directly. This requires accuracy, and the ability to reach those structures via penetration.

Hollow points limit penetration in relation to FMJ.

Well what about momentum vs energy?

Lets move to handgun rounds in effective hollow point designs, in relation to self defense.

We know that the cavitation caused will not be very significant.

They should stop within the body of a person baring any malfunctions of the ammo. So they will dump 100% of their energy and momentum into the target. (or they will at least expend almost all energy before passing through)

Now... rounds with higher muzzle energy will be felt more by the target... I.E. it will hurt more, and the wound path will be larger due to a bit more cavitation.

In hollow point rounds, this more effective transfer of energy and increased pain, helps stop threats. Even if the wound is not fatal, the added pain adds to the psychological aspect/desire to stop when one knows they have been shot.

This effect can not be counted on solely, as some aggressors may be in a state of mind that limits perceived pain and desire to stop when shot.

Rounds with higher momentum will penetrate more, due to their inertia... I.E. Their resistance to slowing down.

Heavier bullets also have higher inertia, so they too take longer to slow down.

And since momentum has a vector (the bullets are moving) more time means more penetration. Penetration is needed to hit vital structures at other than optimum angles.

Adding gains in velocity, which is more effective at rising energy than momentum, can be difficult due to maximum chamber pressures, while adding bullet weight is relatively easy. Sure, you loose some velocity with the heavier bullet, but not enough to matter most times.

Take 2 loads of 45acp... lets say one is 180gr at 1000fps and the other is 230gr at 900fps.

The momentum of the 180gr is 25.714lbf/s
The momentum of the 230gr is 29.571lbf/s

More momentum, even though we lost 100fps and gained only 50gr... to get the same momentum from the 180gr you need 1150fps

This is why "heavy for caliber" tend to penetrate deeper (all other factors being equal, like bullet type/design) This is also why they perform more consistently during tests, and are preferred by many shooters for defense.

The added momentum over lighter bullets, plus the added inherent inertia of more mass, means more penetration. As I said, they team up and work together.

Sure, more muzzle energy also increases penetration, but without the aid of the mass inertia, it tends to not perform as consistently.

This is how I understand the physics/math... I could be wrong... it has been 10 years since college, and I am an electronics tech, so this type of figuring doesn't come up in my day to day life/work. I got bored with nothing to do today, so we end up with this long post. :p
 
Last edited:
Good summary.

32.174 is a better approximation for G (the number of pounds in a slug) than 32.163, but it won't really change the results from a practical standpoint.
 
marine6680,

Yours, even with the slight numerical correction offered by JohnKSa, is one of the better perspectives on the topic that I've seen in a long time.

Nice job and thanks for splitting the paragraphs like you did- nice 'n easy on these old eyes.

Nicely done. :)
 
@ marine6680-

What you've said agrees with the vast majority of what I've read (MacPherson, Schwartz, Fackler, Roberts, et. al.) so far about the topic. Hell, I'm impressed- maybe you missed your calling. ;)
 
Nanuk, if hunting big game with a .44 you probably have not been using JHP.

I have seen a Remington 240 JHP fail tp penetrate the shoulder cartilage of a 200ish pound boar. The round in question was fired from a Marlin 94, and its velocity resulted in rapid expansion and poor penetration.

It isn't just velocity; it isn't just sectional density; it isn't just bullet construction. It is how all three work together that determine whether a load is a good choice for a given target type.
Click to expand...

My big game hunting has been North Dakota Whitetail and Mule deer @+/- 200 lbs. For that thin skinned large game I do use hollow points in 44 mag, I am actually partial to Barnes X bullets. I have never shot a Boar or a bear and if I did would probably use a 240 LSWC at around 1400-1500 fps. I agree with you about how all three work together and should be considered, that is why I run a Bonded HP at high velocity.

To be sure my I like my big magnums, it is just easier to conceal and more practical to carry a Glock for SD.
 
In a defensive rd for a handgun which is more important to consider....muzzle velocity or muzzle energy?
Click to expand...

Short answer- all other things being equal, energy is more important than velocity.

There are plenty of other factors- ballistic and otherwise- that are as important, or more important.
 
Marine6680,

I agree with most everything you posted, it is difficult to argue physics.

However,

Now... since rifles have inherently more energy and momentum than handguns, if a rifle round only transfers 30% of its energy, that is a far greater amount than say 30% from a 9mm... Which is why rifle rounds create more cavitation in the body.
Click to expand...

I always hear people say rifle velocities VS pistol velocities. I really dislike that type of blanket statement or when people cherry pick rounds (9mm VS a rifle). I have never heard an "expert" give a velocity floor. What I have seen, in 3 decades of law enforcement and what those in the business of forensic examination seem to verify is that at around 1300 fps handgun bullets start becoming quite amazing performers on humans.

I believe that is why historically the 125 Grain 357 magnum at 1350-1450 FPS and the 115 grain 9mm +P+ at the same velocity seem to defy logic as they perform poorly in gelatine, but work wonderfully on the street. The 180 Grain 44 Magnum fits into this category as well.
 
Nanuk, what of the case where the LEO put several 125 JHP .357 into the torso of a large male, but all created shallow wounds, and large male got lucky hit on LEO with mousegun, severing artery.? (I remember the account, but not the names.)
 
Not all rifle rounds are created equal and neither are pistol rounds. But on average... the statement about velocity is true.

It is a combination of velocity, size, shape... Heavier bullets can do well at lower velocities, usually because they are larger diameter caliber. Flat bullets cavitate more than pointed... but there is a floor below which standard readily available bullets will not create large cavitation in relation to their size. This ratio of cavitation size to bullet size is important.

Even a golf ball will cavitate, and at relatively low velocities compared to a bullet. But that is in plain water, and penetration would be low.

Which is another problem... shallow cavitation. Which is what handgun hollow point rounds do. They expend most of their energy quickly in the first few inches, then its just direct displacement damage after that until it stops. And they can't just redesign to slow down the expansion rate, as then what little cavitation there is would be spread out and it wouldn't be as effective at causing pain.

22lr hyper velocity hollow points are another example, massive cavitation in relation to their size, but very shallow.

I would say the 1300fps mark may be close to the lower end of velocity that gives good cavitation across a good range of bullet shapes and types... 1300-1400fps seems about right, from the tests I have seen of the 22lr mini mags at 1200fps and velocitors at 1400fps. The difference between them is interesting.
 
Last edited:
481 said:
Y'know, muzzle energy is dependent upon the bullet's velocity so if you find velocity to be less important than muzzle energy, you are saying that you find muzzle energy to be less important.
Click to expand...
First, when asked to compare two factors, unless they are of exactly equal importance only one can be less important. Once one has been rated as less important, the one that is more important cannot be less important than the one that IS less important.

Second, muzzle energy is related to velocity, but it is also related to bullet weight. If you have two rounds of equal caliber (diameter) and equal velocity, the one using the lighter bullet will carry less energy. Recognizing that, your comment makes no sense because it ignores the third variable in the equation.

But the OP didn't ask anything about bullet weight -- he asked if we consider velocity or muzzle energy to be more important. Of those two, I think muzzle energy is the more important. Muzzle energy can be achieved by using heavy bullets going slow, or light bullets going fast. He didn't ask about that, so I didn't try to answer a question that wasn't asked.
 
AB, I think what 481 was saying that while energy goes up in direct proportion with an increase in mass, it goes up as the square of a velocity increase.

Twice the mass, twice the energy. Twice the velocity, four times the energy. So, if energy is the overriding concern, the answer will typically be to increase velocity, rather than mass.

Momentum goes up in linear fashion with both mass and energy.

The resistance of a medium to a bullet will be a function of energy. Look at what happens, for instance, when fast moving objects hit the water.

The momentum of the bullet is what will fight the drag from the medium. The slower, heavier bullet will have the advantage.
 
Nanuk, what of the case where the LEO put several 125 JHP .357 into the torso of a large male, but all created shallow wounds, and large male got lucky hit on LEO with mousegun, severing artery.? (I remember the account, but not the names.)
Click to expand...


You are thinking of trooper Coates from South Carolina.

http://www.odmp.org/officer/420-trooper-mark-hunter-coates\

http://www.youtube.com/watch?v=2ca-PAWBMnk

I do not believe they were shallow wounds, they just did not hit anything vital. If you watch the video you can see the fight, imagine the difficulty in placing the shot. The BG placed the trooper in a bear hug and fired his 22 into the troopers armpit.


It was actually the 145 Grain STHP that trooper Coates was using.
 
MLeake: said:
AB, I think what 481 was saying that while energy goes up in direct proportion with an increase in mass, it goes up as the square of a velocity increase.

Twice the mass, twice the energy. Twice the velocity, four times the energy. So, if energy is the overriding concern, the answer will typically be to increase velocity, rather than mass.

Momentum goes up in linear fashion with both mass and energy.

The resistance of a medium to a bullet will be a function of energy. Look at what happens, for instance, when fast moving objects hit the water.

The momentum of the bullet is what will fight the drag from the medium. The slower, heavier bullet will have the advantage.
Click to expand...

MLeake, you read me perfectly. :) You did a better job of explaining it than I did. Very nice. :cool:

MLeake: said:
The resistance of a medium to a bullet will be a function of energy. Look at what happens, for instance, when fast moving objects hit the water.
Click to expand...

Yes, that is how I understand the phenomena- the equation for quadratic drag (it's more about viscous drag at lower velocities, inertial drag at higher ones) being the basis of that understanding.
 
You must log in or register to reply here.
Back
Top