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Old September 22, 2012, 01:44 PM   #1
IMTHDUKE
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Which is more important in ballistics?

In a defensive rd for a handgun which is more important to consider....muzzle velocity or muzzle energy?
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Old September 22, 2012, 01:48 PM   #2
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Velocity and bullet construction - ft lbs are meaningful and once you are north of 400 ft lbs then more is not necessarily better
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Old September 22, 2012, 02:30 PM   #3
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The bullet's momentum- mass times velocity.
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Old September 22, 2012, 02:50 PM   #4
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How big of a hole it'll poke through meat & bone and do it in a straight line.
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Old September 22, 2012, 03:07 PM   #5
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481 hit the nail on the head~momentum is what gets the bullet to where it'll do the most harm.

Very high velocity bullets often blow up before reaching home, expanding too much too soon.

That's why the old .45 Colt remained so popular for so many years, as did the .45 ACP hardball round.

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Old September 22, 2012, 03:13 PM   #6
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Both are of use in evaluating potential performance but, if you have to pick one, I'd say muzzle energy is more important than velocity. Which would you rather get shot with, a .22LR at 1300 feet-per-second or a .45 ACP at 850 feet-per-second?
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Old September 22, 2012, 04:09 PM   #7
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To me, accuracy trumps 'em both.
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Old September 22, 2012, 04:33 PM   #8
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Reliability, then accuracy, then adequate penetration, then shootability, and last expansion as I see it.

I like Federal HST standard pressure at the heaviest weight per caliber: 230 for .45, 180 for .40, and 147 for 9mm. All are subsonic, but all move at good velocity (850 .45, 1000 for .40, 990ish for 9mm). All get around 12-12.5" in gelatin, do well (for caliber) with barriers, and offer reliable expansion.
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Old September 22, 2012, 05:23 PM   #9
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Energy is more important than velocity when comparing possible SD rounds but there are things more important than energy. Accuracy and reliability should also be considered.
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Old September 22, 2012, 05:33 PM   #10
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With an adequate sized bullet, more muzzle velocity generally gives you more energy, the more energy you have the more you have to work with. With modern bonded hollow points, you can move lighter bullets faster, mushrooming them to make a bigger hole and the energy allows them to penetrate deeper. 2 excellent examples of this are the 125 Grain Bonded gold dot loaded in the 357 Sig which gives you 1450 FPS from a Glock 31, and the 155 Grain gold dot 10 MM load moving at 1500 FPS.
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Old September 22, 2012, 05:49 PM   #11
481
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Quote:
Originally Posted by Aguila Blanca:
Both are of use in evaluating potential performance but, if you have to pick one, I'd say muzzle energy is more important than velocity.
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.

Quote:
Originally Posted by Aguila Blanca:
Which would you rather get shot with, a .22LR at 1300 feet-per-second or a .45 ACP at 850 feet-per-second?
Neither. I also wouldn't want to be hit with a BB at 300 fps, a large stone, or a piece of doggie-poo, but that doesn't mean that they'd make a good choices for self-defense either.
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Old September 22, 2012, 05:58 PM   #12
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Neither accuracy nor reliability fall under ballistics.

Initial muzzle velocity is of importance for long range shots. The quicker a bullet gets to its target, the less time gravity and wind have to act on that bullet. Gravity is constant, wind isn't.

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Old September 22, 2012, 06:03 PM   #13
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The most important consideration of a self defense round is hitting the target with it.
The gun and ammo choices are the least of it.
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Old September 22, 2012, 06:13 PM   #14
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Quote:
Originally Posted by Bob Wright:
Neither accuracy nor reliability fall under ballistics.
Good point, Bob. The only thing that matters is that the bullet hits something important and that it has the momentum to get there.
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Old September 22, 2012, 06:23 PM   #15
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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.

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.

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Old September 22, 2012, 06:37 PM   #16
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SD .38 loads are DEWC 148 gr over +P doses of Unique. Matter of fact, I shoot anything with them. It isn't anything but sectional density at that range. 900 plus fps is a pretty mild load, after all.
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Old September 22, 2012, 07:05 PM   #17
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Quote:
In a defensive rd for a handgun which is more important to consider....muzzle velocity or muzzle energy?
Excellent question,,,
I must have typed and then changed my answer a dozen times.

In all honesty - I'm stumped on this.

There's just simply too many ways it can be answered.

Quote:
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.
True - very true... I typed something like that also, then got to thinking about it and erased the whole thing.

Just for conversation's sake,,
Let's say you were handed a round of ammunition.
You look at the base and see that it's a .357Mag case.

Other than what a visual inspection shows, you can't have any other information about that round - except -
It's muzzle energy
or
It's muzzle velocity.

Armed with that number, and, based on your experience usinng the caliber in question,,,

Which would you choose to make the most educated guess as to how effective that round would be?

I started to say, ME since if I knew the ME, and based on the thousands of .357" bullets I've loaded/shot over the years, if I knew the ME I could back out the MV.
Then the more I thought about it, the more I thought if I knew the MV, I could make a pretty accurate stab at the ME..that would be easier and quicker..

Then, the more I thought about it, the more I started to wonder,,,
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Old September 22, 2012, 07:20 PM   #18
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Quote:
Originally Posted by Hal:
Just for conversation's sake,,
Let's say you were handed a round of ammunition.
You look at the base and see that it's a .357Mag case.

Other than what a visual inspection shows, you can't have any other information about that round - except -
It's muzzle energy
or
It's muzzle velocity.

Armed with that number, and, based on your experience usinng the caliber in question,,,

Which would you choose to make the most educated guess as to how effective that round would be?
That's an interesting question- I don't know that I could since it is not possible to determine the KE of either round without knowing the bullet's weight or velocity.

For instance, both of the .357 Mag rounds could be marked as having a KE of 583 fpe which means that one could be a 125 gr. bullet at 1450 fps and the other a 158 gr. JHP at 1290 fps- or they could be of other weights at other muzzle velocities that's give me that number. Both would have 583 fpe of KE, but not knowing the weights or the velocities of each, I'd be making the choice in a relative vacuum.

Forced to decide, I'd heft them separately and go with the heaviest of the two since momentum is the best measure of a bullet's ability to penetrate soft tissue.

Conversely, if I were selecting a round to defeat a thin, hard barrier like a sheet of mild steel, I'd opt for the lighter, faster one since kinetic energy is the best measure of a bullet's ability to penetrate/defeat those types of barriers.
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Old September 22, 2012, 07:20 PM   #19
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Quote:
In a defensive rd for a handgun which is more important to consider....muzzle velocity or muzzle energy?
481 above made a correct point, seems to me.

Velocity and energy are directly related and can't be separated.

A bullet in the chamber has potential energy. Once the primer is struck that becomes kinetic energy. Kinetic energy (K) is measured in foot pounds of energy (ft.pds). This is a unit that measures the ability of a round to do work. The work of overcoming the friction of the barrel, bucking the wind, some is lost to noise, penetrating the target, expanding, etc.

As velocity increases so does the kinetic energy available to a round. This is why a .357 Magnum round is more powerful than a 38 Spl. and why a 44 Mag. is more powerful than a 44 spl.

But it's only one part of the picture. The type of bullet chosen is critical. This includes the construction of the bullet as well as it's weight. The bullet should be matched to the task.

A 230 gr. 45. acp bullet at 475 fps has about 390 ft lbs of energy available to it to work with. This is more than enough for self defense and deer or hog at reasonable distances provided the right type bullets are selected.

The weight of the heavier bullet allows momentum to work in it's favor. But here also bullet construction matters. If a jhp bullet designed for self defense against humans is used to hunt hog the bullet may expand too rapidly and decrease momentum and hinder penetration. A round needs both the proper construction and enough energy to expand and penetrate.

Penetration requires adequate energy. Energy is expended in penetration.

Energy figures tend to be more useful to the shooter with long guns than short in my opinion.

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Old September 22, 2012, 07:41 PM   #20
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One of the best way to test is to get some medium such as ballistic gelatin or Duxseal, even clay, and fire bullets into it.

The best load will produce a large cavity midway in the medium. Some will produce no cavity, other bullets will produce a large surface cavity.

Try your bullets on crows, groundhog, deer and other animate crtiiers as the law allows. Autopsy what you've shot.

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Old September 22, 2012, 08:17 PM   #21
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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.
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Old September 22, 2012, 08:21 PM   #22
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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.

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Old September 22, 2012, 08:31 PM   #23
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Quote:
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.
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.

Quote:
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.
Just curious, what velocity was that 44 traveling at? I understand the penetration because I have been hunting with 44's for 30 years.
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Old September 22, 2012, 09:48 PM   #24
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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.
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Old September 22, 2012, 09:55 PM   #25
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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.

Last edited by marine6680; September 22, 2012 at 10:52 PM.
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