Which is more important in ballistics?


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IMTHDUKE
September 22, 2012, 03:43 PM
In a defensive rd for a handgun which is more important to consider....muzzle velocity or muzzle energy?

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481
September 22, 2012, 04:11 PM
Momentum at impact (mass times impact velocity) and what the bullet hits. So...velocity.


:)

Doc3402
September 22, 2012, 04:37 PM
If you mean the ratings on the box of ammo, neither one. Too many things can affect the actual MV and ME. Barrel length and handgun condition are the two most obvious.

481 makes a very good point, but I think it's slightly misstated. Energy at impact is what I think he meant. Cross-sectional design is also important. More energy will be transmitted to the target if you use a flat nosed bullet than if you use something pointy.

Since you did state handgun in your post I think it's important to understand that shot placement is probably your most important consideration. For all intents and purposes hydrostatic shock is not a factor in most handgun calibers. The velocities are too slow.

481
September 22, 2012, 07:15 PM
481 makes a very good point, but I think it's slightly misstated. Energy at impact is what I think he meant.

Nope, I meant momentum.

Newton's laws of motion dictates how a bullet will behave as it penetrates soft tissue. The forces acting on the bullet arise from a decrease in momentum brought about by a change in its velocity (deceleration, in this case) are expressed as F = ma, so momentum is indeed what I meant.

Rexster
September 22, 2012, 07:22 PM
If it can make a hole, reliably, deep into the important bits, that is what is most important.

Velocity IS a component of energy. Muzzle velocity IS a component of muzzle energy. If all else stays the same, as velocity goes up, so does energy.

481
September 22, 2012, 07:38 PM
Velocity is also a component of momentum, hence p = mv. Penetration is a direct function of momentum and the best way to look at events of this type.

Zak Smith
September 23, 2012, 02:33 AM
Check the FBI protocol for testing terminal ballistics. It uses neither.

btg3
September 23, 2012, 08:41 AM
Muzzle velocity IS a component of muzzle energy
^^^This.
Velocity is just velocity.
Energy includes mass and velocity -- making it more significant than velocity alone.

In a defensive rd for a handgun which is more important to consider...
The question is flawed. As noted by other posters, there are more significant factors to consider.

1911Tuner
September 23, 2012, 09:08 AM
Velocity...Energy...Momentum. All part of the equation, and all variable. Mass is the only constant. The British worked it out two and a half centuries ago. "Heavy ball/Light charge."

scaatylobo
September 23, 2012, 09:27 AM
In my not so humble opinion.

Its accuracy and YOUR ability to hit a small moving target with ANY caliber.

After that,my vote goes to ability to penetrate soft tissue to a depth of 10 or 12 inches.

Kleanbore
September 23, 2012, 09:33 AM
Neither. Given the same mass, energy is determined by velocity.

Energy, or work, is one of the several things that determine penetration. Penetration and diameter determine effectiveness, along with point and direction of impact.

There are people on the wonderful world wide web who contend that momentum is the determinant of penetration, usually in the context of archery. They could use a physics course. Momentum will define two things: recoil, and how fast the target with the bullet in it will move after impact. The latter is very insignificant.

Consider that braking distance of an automobile varies with the square of the velocity. Same thing.

481
September 23, 2012, 12:06 PM
There are people on the wonderful world wide web who contend that momentum is the determinant of penetration, usually in the context of archery. They could use a physics course.


Duncan MacPherson, an MIT educated Aerospace Engineer, seems to believe otherwise and argues below that momentum is a valid way to model terminal ballistic behavior to include penetration. His momentum-based model predicts penetration and I doubt that anyone could argue that he is in need of a physics course. :confused:

Excerpt from "Bullet Penetration" by Duncan MacPherson:“. . . every now and then someone wants to analyze or think about a problem involving energy, and when they attempt to do this without really understanding energy or other thermodynamic concepts the result is unfortunate. One such problem is the analysis of any of the various aspects of terminal ballistics; some individuals with inadequate technical training and experience have unwisely and unproductively attempted to use energy concepts in the analysis of bullet impact and penetration in soft tissue. (Many others have simply assumed that energy is the dominant effect in Wound Trauma Incapacitation; this assumption is even more simplistic than the attempt to actually analyze the dynamics problem with energy relationships, and is no more successful).

Any attempt to derive the effect of bullet impact in tissue using energy relationships is ill advised and wrong because the problem cannot be analyzed that way and only someone without the requisite technical background would try. Many individuals who have not had technical training have nonetheless heard of Newton’s laws of motion, but most of them aren’t really familiar with these laws and would be surprised to learn Newton’s laws describe forces and momentum transfer, not energy relationships. The dynamic variable that is conserved in collisions is momentum; kinetic energy is not only not conserved in real collisions, but is transferred into thermal energy in a way that usually cannot be practically modeled. The energy in collisions can be traced, but usually only by solving the dynamics by other means and then determining the energy flow.

Understanding energy and how it relates to bullet terminal ballistics is useful even though energy is not a useful parameter in most small arms ballistics work.”

2zulu1
September 23, 2012, 01:00 PM
^^^^^^

MachIVshooter
September 23, 2012, 02:54 PM
Muzzle energy is the easiest/quickest way to compare the relative capability of cartridges, but it's certainly not the only thing to consider, and you have to keep it in the same ballpark (for example, a .223 from a rifle and a .44 mag from a handgun have similar energy, but very different wounding mechanisms).

KE does largely determine a cartridge's ability to do work, work being bullet expansion & penetration. But it's not universal; The weight and construction of the bullet have to be appropriately matched to the power to achieve the desired performance. You can push a 90 gr. bullet out of a 9mm to velocities that will rival the energy of moderate .357 mag loads, but that .357 will be using a 125, 140 or 158 gr. bullet that is designed to hold together and acheive penetration, whereas that 90 gr. .355" pill is meant for the 900-1,100 FPS velocities of a .380, and will literally blow up in the medium when driven to 1,600+ in a 9x19mm +P load. So even though both that 9mm 90 gr. load and .357 mag 158 gr. load will generate around 550 FPE, the .357 load will be far more effective.

My personal feeling for defensive handguns is that more energy is better up to the level of full house 10mm, but it should be achieved using mid to heavy weight bullets for the caliber. Heavy bullet loads will have lower energies than the lighter bullets in a given cartridge, but almost universally achieve deeper penetration. I'd rather have a 124 gr. 9x19mm load making 375 FPE than the aforementioned 90 gr. load at 550 FPE.

R.W.Dale
September 23, 2012, 02:59 PM
I'm gonna give the same answer as I dis on the other forum Whee you asked this

The only thing that matters is what you put a bullet hole in.

Velocity and energy don't stop bad guys or kill game in the field. Bullet holes on the otherhand do.


You need shot placement, penatration, reliability and then energy-expansion

MachIVshooter
September 23, 2012, 03:36 PM
The only thing that matters is what you put a bullet hole in.

That's kinda the whole point of considering energy and momentum. A perfectly placed shot that dos not achieve adequate penetration is no better than a poorly placed shot that gets through but misses the structure. And a big hole is better than a small hole. To achieve that adequate penetration and large hole, you need energy and momentum.

No one is arguing that shot placement isn't top priority, but it would be asinine to imply that a 3mm Kolibri can be as effective as a .45 ACP with a hole in the same place. Stopping an attacker isn't popping a balloon. Ballistics matter.

R.W.Dale
September 23, 2012, 03:41 PM
Its no less asinine to imply that massive amounts of energy or velocity (at handgun levels) in any way make up for inferior shot placement.

Folks watch slow motion gel tests of modern jhp's in service handguns and get this false impression that the human body cannot cope with what they're seeing in the gel. This is a false assumption bourne out by the fact that over 80% of handgun gunshot victims survive

WardenWolf
September 23, 2012, 03:46 PM
From what I've seen in ballistics tests on Brass Fetcher, velocity matters a lot more than bullet size or weight. For example, comparing 7.62x25 (a .31 caliber projectile) to 9mm (a .357 caliber projectile), both using Speer Gold Dot hollowpoints, the Tokarev round is noticeably more destructive, inducing greater hydrostatic shock that is also much more violent (it produces a VERY pronounced cyclonic effect). Note that the Tokarev round is moving around 1400 FPS, whereas the 9mm round is moving around 1200 FPS. Bullet weight was 115 grains versus 124 grains.

Another example of this is exhibited with .45 ACP ammo. The heavier 230-grain bullet was very unimpressive, exhibiting worse performance than the 9mm round. However, the 203-grain bullet, with its higher velocity, proved devastating, far more so than 9mm. Again, both bullets were Speer Gold Dots. Velocity once again shows itself to be the key factor.

Of course, velocity also translates directly to muzzle energy. Because of the way energy is calculated, a lighter bullet traveling at a higher velocity often carries more energy than a heavier bullet traveling slower. Comparing from 124 grains at 1200 FPS in 9mm to 115 grains at 1400 FPS in 7.62x25, you lose approximately 8% of your weight, but gain more than 28% velocity, making for a substantial increase in overall energy.

MachIVshooter
September 23, 2012, 03:47 PM
Its no less asinine to imply that massive amounts of energy or velocity (at handgun levels) in any way make up for inferior shot placement.

Are you just wanting to argue for the sake of arguing? I have to assume so, since I made it clear that:

No one is arguing that shot placement isn't top priority


inducing greater hydrostatic shock that is also much more violent

Hydrostatic shock is not a reliable wounding mechanism at handgun velocities. Bullets moving slower than ~2,000 FPS do damage by crushing and tearing tissue directly contacted by the bullet. Yes, there is often some peripheral damage done by the temporary cavity, but again, that is not a reliable component with handgun rounds. Unless you're a Michael Courtney deciple, in which case reality isn't relevant...........

WardenWolf
September 23, 2012, 03:55 PM
Well, it depends. The Tokarev's hydrostatic shock was actually cyclonic. It was twisting, not just expanding. That would cause a lot more damage with regards to tearing tissues apart.

R.W.Dale
September 23, 2012, 03:56 PM
Its my observation that handgun cartridges seem to fall into groups it tiers of similar effectiveness when loaded with top tier defense loads for each.

Sub service or "pocket" pistol calibers

32-380-38spl ect

Not terribly effective, IMO best used with the deepest penatration loads for each expansion severely hampers penatration


Service calibers

9-40-357sig-mag-45 ect

Can drive modern expanding ammo hard enough to provide adequate penatration.

Hunting calibers or magnums

44mag-hot colt-10mm-some357-ect

Can drive bullets too hard if careful selection isn't made. Doesn't seem to bring anything to the anti 2 legged defense role compared to service calibers.

Then IMO you have a fourth set of big bore calibers that retain a satisfactory level of effectiveness sans expansion starting with 44spl +


Within these tiers terminal performance is so similar that factors of accuracy, recoil, platform and capacity become the primary considerations. With a few cartridges like 38spl, 10mm, 357mag and even 45acp having the ability to bridge the gaps in between depending on the platform and exact loading

btg3
September 23, 2012, 03:58 PM
True or false... Selection of handgun caliber will make the greater difference as compared to selection of a particular self-defense load within a given cailber.

Frank Ettin
September 23, 2012, 04:03 PM
Been through this before, but let's do it again.

There are four ways in which shooting someone stops him:

psychological -- "I'm shot, it hurts, I don't want to get shot any more."
massive blood loss depriving the muscles and brain of oxygen and thus significantly impairing their ability to function
breaking major skeletal support structures
damaging the central nervous system.

Depending on someone just giving up because he's been shot is iffy. Probably most fights are stopped that way, but some aren't; and there are no guarantees.

Breaking major skeletal structures can quickly impair mobility. But if the assailant has a gun, he can still shoot. And it will take a reasonably powerful round to reliably penetrate and break a large bone, like the pelvis.

Hits to the central nervous system are sure and quick, but the CNS presents a small and uncertain target. And sometimes significant penetration will be needed to reach it.

The most common and sure physiological way in which shooting someone stops him is blood loss -- depriving the brain and muscles of oxygen and nutrients, thus impairing the ability of the brain and muscles to function. Blood loss is facilitated by (1) large holes causing tissue damage; (2) getting the holes in the right places to damage major blood vessels or blood bearing organs; and (3) adequate penetration to get those holes into the blood vessels and organs which are fairly deep in the body. The problem is that blood loss takes time. People have continued to fight effectively when gravely, even mortally, wounded. So things that can speed up blood loss, more holes, bigger holes, better placed holes, etc., help.

So as a rule of thumb --

More holes are better than fewer holes.
Larger holes are better than smaller holes.
Holes in the right places are better than holes in the wrong places.
Holes that are deep enough are better than holes that aren't.
There are no magic bullets.

And sometimes a 9mm might not be enough because sometimes even a .357 Magnum isn't necessarily enough. LAPD Officer Stacy Lim (http://www.lapdonline.org/inside_the_lapd/content_basic_view/27327#Stacy%20Lim) was shot in the chest with a .357 Magnum and still ran down her attacker, returned fire, killed him, survived, and ultimately was able to return to duty.

MachIVshooter
September 23, 2012, 04:07 PM
True or false... Selection of handgun caliber will make the greater difference as compared to selection of a particular self-defense load within a given cailber.

That's not a question so easily answered. The absolute, top-dawg premium load in a .32 ACP is still not going to be as effective as a .44 Spl. cowboy load.

On the other hand, a good, modern JHP 9x19mm load will likely outperform a .45 ACP FMJ.

Best answer: Choose a capable cartridge, find a platform that suits your needs, choose a quality load that performs well, then practice, practice, practice.

My absolute minimum for a defensive round is 200 FPE with a good bullet, whether it's a .380 or a .32 H&R magnum. Anything less than that, you're either making too small a hole or not getting enough penetration (or both). Whenever possible, I carry 10mm. It's got the power to drive a heavy bullet deep and expand it wide in any 2-legged threat.

MikePGS
September 23, 2012, 04:09 PM
"Placement is power." Stephen A. Camp

easyg
September 23, 2012, 04:33 PM
Its no less asinine to imply that massive amounts of energy or velocity (at handgun levels) in any way make up for inferior shot placement.
No one here is making this argument.

Everyone here agrees that shot placement is of the utmost importance.

But that does not mean that caliber, velocity, energy, and bullet design doesn't matter.
All of that matters a great deal.

As for the original question....which is more important, velocity or energy?
Energy is more important.

Whether one prefers a heavy and slower high energy round, or a light and faster high energy round, it does not matter so long as adequate energy is reached.

Now exactly what is the adequate amount of energy?
That is the real debate.

I think that any handgun load that offers 400+ ft. lbs. of energy will work just fine for stopping aggressive human threats, so long as it's not too powerful for the shooter to quickly and accurately put lead on target.

481
September 23, 2012, 04:43 PM
Its no less asinine to imply that massive amounts of energy or velocity (at handgun levels) in any way make up for inferior shot placement.

Folks watch slow motion gel tests of modern jhp's in service handguns and get this false impression that the human body cannot cope with what they're seeing in the gel. This is a false assumption bourne out by the fact that over 80% of handgun gunshot victims survive

I agree.

Most people do not realize that the T/Cs shown in those videos are nowhere near large enough to exceed the elastic strength of the vast majority of the tissues that a bullet will travel through as it passes through a human body.

The T/Cs in the videos appear to be impressive, but as they say- "Appearances can be deceiving."

Friendly, Don't Fire!
September 23, 2012, 05:06 PM
This is one of those arguments that has no right or no wrong answers.

It all depends on exactly what is being shot -- at exactly what distance -- and, whether or not overpenetration can (or cannot) be an issue.:rolleyes:

Kleanbore
September 23, 2012, 05:08 PM
MacPherson is correct when he observes the following:

The dynamic variable that is conserved in collisions is momentum; kinetic energy is not only not conserved in real collisions, but is transferred into thermal energy in a way that usually cannot be practically modeled. The energy in collisions can be traced, but usually only by solving the dynamics by other means and then determining the energy flow.

But: the fact that momentum is conserved in either an elastic (think billiard balls) or inelastic (punching bag) collision does not have a thing to do with penetration. It simply enables one to determine the velocity of the target with the bullet in it if one knows the mass of the target, the mass of the bullet, and the velocity of the bullet upon impact, and if the bullet does not exit the target. McPherson would agree with that, were he alive today. But that's something one does not need to know.

One can also solve for the bullet's velocity upon impact by working backwards from the mass of the bullet, the mass of the target , and the velocity if the target plus the bullet after impact. Again, the equations used for that purpose involve momentum. That's how a ballistic pendulum works. At least some of us have done that in engineering school. I did it in high school, too. One wold not measure velocity that way today, but it's and excellent teaching device.

The conversion of kinetic energy into thermal energy is part of what stops the bullet--i.e., what determines penetration--just as the heating of your brakes is what stops your car. The kinetic energy prior to impact is therefore a major determinant of penetration, (how far the bullet travels into the target after impact), and your car travels after the brakes are put on.

What it takes to put your car or a bullet into motion is work, which is by definition energy, thermal and kinetic. It's the same thing when it comes to stopping either one, or anything that is moving, for that matter. That's indisputable. And no, I wouldn't attempt to model it. But one can measure the behavior of the items. Many of us have done that. too.

Penetration in a given substance will be determined by a number of things, including the shape of the bullet, the mass, how it deforms, and how fast it is going. But it is the square of the velocity with which penetration will vary, all other things being equal.

Back to the OP's question: what determines a bullet's effectiveness is what it damages. And adequate penetration is a big part of the answer to that question, along with wound channel and where the bullet strikes. That's consistent with McPherson's conclusions.

By the way, at handgun velocities, the only important thing that energy affects is penetration. Forget "energy dump", "shock", whatever. That's consistent with McPherson's conclusions, too.

Just an aside: the term "hydrostatic shock" is a misnomer. I'm a little embarrassed to say that I ate that stuff up while reading Jack O'Connor's books about hunting rifles at the same time I was studying engineering. I should have known better. But we all know what people mean when they use the term.

coalman
September 24, 2012, 03:24 AM
Momentum. I favor mass. I want heavier moving as fast as possible opposed to lighter moving as fast as possible.

2zulu1
September 24, 2012, 03:25 AM
I'm not sure how billiard balls or punching bags relate to fluid dynamics, but I do use MacPherson's book as a reference source. I needed tutoring to grasp some of the formulas he used to validate the momentum model as it related to bullet penetration. An engineer should not have any issues understanding MacPherson's empirical research.

Here's a link to Double Tap's gel data for a number of handgun bullet designs and calibers.

http://www.glocktalk.com/forums/showthread.php?t=336612

As we can see, there is a bullet penetration overlap between calibers independent of kinetic energy. Of particular interest for our discussion is the comparison between the much higher KE 10mm/180gr Gold Dot and the 45auto/230gr Gold Dot. In spite of the fact that the 10mm had a significant KE advantage, both bullets expanded to the same diameter and penetrated the same distance in ballistic gel.

Given equal expansion, the 230gr Gold Dot retained more of its sectional density than the 180gr. Both bullets are in the same sectional density group and both loadings basically share the same momentum.

Given McNett's ballistic gel data, there still isn't any way to predict wound trauma Incapacitation times.

1911Tuner
September 24, 2012, 06:27 AM
Momentum. I favor mass. I want heavier moving as fast as possible opposed to lighter moving as fast as possible.

I'm also in the mass/momentum corner, but with higher and higher velocities, you can reach the point of diminishing returns. Newton 3 will spoil the show. The harder the bullet hits the target, the harder the target hits the bullet. This is why a car being pushed for absolute top speed eventually runs into a stalemate with the wind...which is essentially "penetrating" a fluid medium.

Studying long-range ballistics tables will reveal much on this issue.

Two .30 caliber bullets with similar shapes and BCs...150 and 165 grains at 2800 fps and 2600 fps initial velocities...the lighter, faster bullet loses a greater percentage of its initial velocity at 100 yards than the heavier, slower bullet. At 400 yards, the speed gap is rapidly closing. At about 500 yards, the 165 catches the 150 and passes it, beating it in both energy and momentum.

Certainly the ballistic coefficient factors in, but there's more to it than simply that. Sectional density and how efficiently the bullet conserves its momentum are equally important. Here, the advantage goes to the more massive/heavier bullet. The old-timers observed this, and they said that the heavy bullet "carried" better than the light one. The 19th century buffalo hunters favored heavy bullets for good reason, even with lower velocities and rainbow trajectories.

bikerdoc
September 24, 2012, 06:38 AM
So as a rule of thumb --

More holes are better than fewer holes.
Larger holes are better than smaller holes.
Holes in the right places are better than holes in the wrong places.
Holes that are deep enough are better than holes that aren't.
There are no magic bullets.



This

calaverasslim
September 24, 2012, 07:02 AM
Your all way above me. Energy, Muzzle velocity etc etc etc.

I want a larger caliber bullet, with enough ooomph to put the bad guy down. 9 or 10 or 41 or 44 or 45, whatever I am proficient with and can get a good solid hit.

Kleanbore
September 24, 2012, 10:47 AM
This review (http://www.amazon.com/Bullet-Penetration-Modeling-Incapacitation-Resulting/product-reviews/0964357704/ref=sr_1_1_cm_cr_acr_txt?ie=UTF8&showViewpoints=1) of Duncan McPherson's book ssems to get right to the net upshot, as an engineering professor of mine used to say.

Excerpt:

The three primary components needed for effectiveness with handgun bullets are as follows and in order of importance. These are facts and are indisputable!

1. Bullet Placement - Hit the correct target and you will have better results than if you don't.

2. Bullet Penetration - The farther the bullet goes into the body, the more damage it will cause.

3. Bullet Diameter - The larger the hole the more permanent damage that is done to everything that is in the pathway of that bullet. A 1 inch in diameter hole will cause more permanent damage than a 1/2 inch hole. In other words, a .45 will cause a bigger diameter hole, hence more permanent damage, than a .22.

The same things are concluded in the FBI Handgun Wounding Factors and Effectiveness report.

Knock down power and shock are notably missing from both.

While McPherson (1) showed how it is possible to predict penetration in gelatin from momentum data and from the expansion behavior of the bullet in water and (2) pointed out that kinetic energy (the effects of which many people incorrectly refer to as to as "hydrostatic shock") does not determine projectile effectiveness alone, I really do not think he ever believed that momentum really determines penetration in an inelastic collision; that would go against the laws of physics. He was able to correlate penetration with momentum, given other information that takes into account the effects of, among other things, energy.

Personally, I have no interest in trying to model penetration myself. There are far too many variables. One can learn all one needs to know about penetration in gelatin, through glass, metal, and fabric, from other people's work, and even then the penetration into a 'real' target will be what it turns out to be.

Slow heavy bullet or lighter faster one? Well, in practice, proper "placement" in a three dimensional fast-moving target is to a large extent really a matter of luck, so more rounds, and less recoil, are also key advantages. They help with Frank's contribution that more holes are better than fewer holes and holes in the right places are better than holes in the wrong places.

By the way, lower recoil means less momentum or a heavier firearm.

481
September 25, 2012, 11:51 PM
While McPherson (1) showed how it is possible to predict penetration in gelatin from momentum data and from the expansion behavior of the bullet in water and (2) pointed out that kinetic energy (the effects of which many people incorrectly refer to as to as "hydrostatic shock") does not determine projectile effectiveness alone, I really do not think he ever believed that momentum really determines penetration in an inelastic collision; that would go against the laws of physics.

Well, it seems that he does, and with good reason-

From pages 7 & 8 of Bullet Penetration by Duncan MacPherson:
Many individuals who have not had technical training have nonetheless heard of Newton’s laws of motion, but most of them aren’t really familiar with these laws and would be surprised to learn Newton’s laws describe forces and momentum transfer, not energy relationships. The dynamic variable that is conserved in collisions is momentum; kinetic energy is not only not conserved in real collisions, but is transferred into thermal energy in a way that usually cannot be practically modeled.

Momentum is conserved even in inelastic collisions. MacPherson explains this later in the chapter that I've quoted from (above). If you haven't read the book, I'd recommend it highly. The Schwartz bullet penetration model is also directly derived from F=ma, Newton's second law of motion, which describes momentum transfer (aka "impulse"). I find it hard to believe that both Schwartz and MacPherson are incorrect in their position.

He was able to correlate penetration with momentum, given other information that takes into account the effects of, among other things, energy.

Personally, I have no interest in trying to model penetration myself. There are far too many variables.

If there were too many variables, you wouldn't have the various soft-tissue penetration models set forth by MacPherson (n=400+), Schwartz, (n=700+) and CE Peters (n= ???).

All of them take into account all of the necessary variables, are highly correlated, and quite accurate.

MistWolf
September 26, 2012, 03:26 AM
In a defensive rd for a handgun which is more important to consider....muzzle velocity or muzzle energy?

Neither one. What's most important is terminal performance. Whether using a light fast bullet or slow heavy bullet, what really counts is what that bullet does once it hits the target.

The bullet has to carry enough velocity and weight to get the job done but both are really only a part of the whole picture. Bullet construction has to match velocity and weight to optimize terminal performance. What difference does it make if a bullet is light & fast or heavy & slow if it leaves a long narrow wound channel, or a shallow one because of poor bullet construction and shape?

The FBI specifies pistol ammo must meet a minimum and maximum penetration in ballistic gel (among other criteria). To meet the specifications, manufacturers must balance velocity, mass and construction to give the best terminal performance. Complicating things further is other mission needs such as penetration of barriers, shooting through heavy clothing, price and so on. It's also known that pistol calibers suitable for a duty handgun are unreliable fight stoppers meaning more than one round will probably be needed to stop the altercation.

When selecting self defense ammo, the only thing that's important about velocity and mass is whether or not the load offers enough of both to get the job done. Even so, neither will do any good if the bullet constructed improperly, resulting in poor terminal performance

Kleanbore
September 26, 2012, 03:09 PM
Posted by 481: Momentum is conserved even in inelastic collisions. True, and so I have said. But that does not mean that momentum is the determinant of the distance that an object will travel after being captured in an inelastic collision.

To stop a moving object it is, as you certainly understand, necessary to apply a force to it. And in an inelastic collision, that force involves converting kinetic energy into other forms of energy and/or transferring it to other objects. McPherson said as much.

In stopping a car or truck or a train, friction brakes convert KE to heat, and regenerative brakes convert it to electrical energy.

And guess what: given a constant braking force, the stopping distance is proportional to the square of the initial velocity--to kinetic energy. When I was young, every college freshman studying engineering performed calculations and experiments showing that.

And penetration is nothing but stopping distance.

Things get a little more complex when it comes to the stopping an airplane on a carrier, where the brakes convert some of the kinetic energy to heat, and some of it is transferred to the arresting equipment; and in addressing the the slowing a vehicle reentering the atmosphere from space, where kinetic anergy is converted into heat, until aerodynamic drag takes over, and perhaps unless a parachute is deployed to shed much of the remaining kinetic energy.

If two billiard balls collide (elastic collision), kinetic energy is conserved as kinetic anergy. But if a car smashes into a deformable building, its kinetic energy is shed in several ways--into heat, into material that is put in motion, and so on. The same thing is true in bullets.

As McPherson said, "kinetic energy is not only not conserved in real collisions, but is transferred into thermal energy in a way that usually cannot be practically modeled." So he decided to come up with correlative models based on momentum. But it would be a mistake to conclude that he ever believed that the stopping distance of a car under a braking force (a far easier thing to model--I've done it) was proportional to momentum. Because it is not, and never has been.

If you haven't read the book, I'd recommend it highly. I've thought about it. I have long ago accepted his conclusions about what causes wounding and what does not, but I have no interest in reading about his correlative modeling of penetration, however brilliant it may be.

I'm not one of those fires bullets in to gelatin or pays a lot of attention to test results. I've chosen my carry loads, and I do not continue to meditate about how far a single bullet would go into gelatin.

I do stay up with those fine people here who opine about big and slow vs light and fast, but I do not concern myself much about what a single bullet properly placed would do under ideal circumstances.

So, when it comes to momentum vs energy, I will likely choose low momentum over high, to keep recoil down. And even though a bigger bullet is more effective than a smaller one, there's the issue of round count to keep in mind.

I am not disputing McPherson's assertion that many people have placed too much emphasis on kinetic energy in assessing wounding effectiveness. Full disclosure: until some years ago, I was among them.

Kleanbore
September 26, 2012, 04:49 PM
Posted by twinny: I don['t agree that shot placement means all that much.Say again? Really?

In the first place, combat adrenlin, the noise, the ducking of blows and bullets, is going to make you miss a lot, just as it does those "poorly trained" copsWell, yeah, and that's why I can't get too interested in choosing a firearm on the basis of its performance with a single hit under ideal circumstances.

Furthermore, who says that a hit to one lung is more or less effective than a hit to the spleen or liver? The heart is the same size of target as the brain. So, if you could really count on hitting the heart, why not just aim for the brain? The heart hit is a lot less likely to result in the instant stop that we need, as vs the brain hit.Experts can certainly make informed judgments on what hits would be most effective. They'll say CNS, but that does not mean that anyone would recommend aiming for the brain of a moving target in a violent encounter.

I's pretty well accepted that one should aim for center mass and shoot more than once. A hit to the upper spinal column, or to the ulna 0f the arm holding the gun, or to a tendon holding the knife or maybe a few more....

481
September 26, 2012, 06:58 PM
True, and so I have said. But that does not mean that momentum is the determinant of the distance that an object will travel after being captured in an inelastic collision.

Actually, it is. It is called transfer of momentum. This occurs through the action of a force exacted upon a bullet by contact with a medium which causes it to decelerate. It is F = ma or more specifically F = m ∆v/∆t, which indicates a transfer of momentum. Your statement here says just that:

To stop a moving object it is, as you certainly understand, necessary to apply a force to it. And in an inelastic collision, that force involves converting kinetic energy into other forms of energy and/or transferring it to other objects. McPherson said as much.

And guess what: given a constant braking force, the stopping distance is proportional to the square of the initial velocity--to kinetic energy. When I was young, every college freshman studying engineering performed calculations and experiments showing that.

It is also a momentum transaction.

And penetration is nothing but stopping distance.



As McPherson said, "kinetic energy is not only not conserved in real collisions, but is transferred into thermal energy in a way that usually cannot be practically modeled." So he decided to come up with correlative models based on momentum. But it would be a mistake to conclude that he ever believed that the stopping distance of a car under a braking force (a far easier thing to model--I've done it) was proportional to momentum. Because it is not, and never has been.

That's a good example of F = m (-a) and it is still a mometum transaction. -think "impulse"-func. (F/∆t)--- [ m; ∆v/∆t; ∆v/∆x

Kleanbore
September 26, 2012, 09:06 PM
Posted by 481, in response to "but that [that momentum is conserved in an inelastic collision] does not mean that momentum is the determinant of the distance that an object will travel after being captured in an inelastic collision": Actually, it is.Do you really and seriously believe that the distance required to stop a moving object by applying a constant force is proportional to the velocity, rather than to the square of the velocity? That is, to momentum, rather than to energy?

Have you ever conducted any experiments in that area?

Consider this (http://en.wikipedia.org/wiki/Braking_distance).

The theoretical braking distance can be found by determining the work required to dissipate the vehicle's kinetic energy.[1]
The kinetic energy E is given by the formula:
E = (1/2)mv2, [1/2 m v squared]
where m is the vehicle's mass and v is its speed.

Or if you prefer, see this (http://www.abcs-of-driving.com/sample.htm).

...distance varies at the square of speed, or 4 times as the speed doubles.

That is, distance varies proportionaly with energy.

Yes, force is equal to mass times acceleration. Do not forget that distance is equal to one half the acceleration times the square of the time. We're dealing with force times distance which is work which is energy-- not momentum.

That momentum is conserved is irrelevant--it doesn't the determine distance traveled by the moving object. Energy does. Momentum transfer does determine the resultant velocity of the combined mass of the target and the bullet--which, in the case of a 100kg target and a pistol bullet, is insignificant.

That someone has been able to greatly simplify modeling by correlating distance and other things with momentum is a wonderful thing--but it does not mean that work is equal to momentum, or that force times distance is momentum.

481
September 26, 2012, 11:07 PM
Posted by 481, in response to "but that [that momentum is conserved in an inelastic collision] does not mean that momentum is the determinant of the distance that an object will travel after being captured in an inelastic collision": Do you really and seriously believe that the distance required to stop a moving object by applying a constant force is proportional to the velocity, rather than to the square of the velocity? That is, to momentum, rather than to energy?

Yep, if the force, defined as F = m ∆v/∆t required to decelerate an object is proportional to 1/2MV^2, then it is also proportional to MV (momentum)- the first derivative of 1/2MV^2.

Are they no longer teaching the calculus with physics? :confused:


Consider this (http://en.wikipedia.org/wiki/Braking_distance).

Or if you prefer, see this (http://www.abcs-of-driving.com/sample.htm).

Just as these descriptions are descriptions of energy expenditures over a given distance and period of time, so too are they descriptions of F = m ∆v/∆t- the force you describe acts also to reduce the mass' velocity over that same ∆t changing the object's velocity and therefore, its momentum. It is called impulse.

Yes, force is equal to mass times acceleration. Do not forget that distance is equal to one half the acceleration times the square of the time. We're dealing with force times distance which is work which is energy-- not momentum.

Yep, and distance may also be expressed as s = vt.

Actually, the object posseses both quantities, but in the deceleration of any mass, the most direct way to analyse that motion is through the linear relatonship of s = v∆t with respect to ∆x (distance). It is as valid as any energy based analysis, but far simpler and more convenient to conduct.


That momentum is conserved is irrelevant--it doesn't the determine distance traveled by the moving object.

Oh, it most certainly does. Did you really just say that? :what:

If an object has momentum, it is in motion. When a force acts to reduce or increase momentum, it does so over a period of time causing a change in velocity, ∆v/∆t, and also results in a displacement of the object.

I've never heard Newton's third law of motion, MV = MV, referred to as being "irrelevant".

You see those "V"s up there in the expression "MV = MV" ? That's motion (velocity) which over a period of time equates to distance unless these events occur instantaneously, that is with t = 0. Not possible. So yes, momentum is directly proportional to the distance than an object will move.



That someone has been able to greatly simplify modeling by correlating distance and other things with momentum is a wonderful thing--but it does not mean that work is equal to momentum, or that force times distance is momentum.

Nope, work is proportional to momentum just as it is proportional to energy, but I digress- I covered that derivative relationship in the first sentence of this response.

Kleanbore
September 26, 2012, 11:18 PM
Posted by 481: Yep, if the force, defined as F = m ∆v/∆t required to decelerate an object is proportional to 1/2MV^2, then it is also proportional to MV (momentum)- To be proportional, the relationship must be linear.

What is it that you are trying to say?

Eb1
September 26, 2012, 11:21 PM
Simple:

The size of the hole from an unexpanded bullet.

481
September 26, 2012, 11:34 PM
To be proportional, the relationship must be linear.

What is it that you are trying to say?

If that is the case, then how can you say this? :confused:



That is, distance varies proportionaly with energy.

Energy vs. distance traveled (∆V w/respect to ∆x/∆t) is not a linear function-

Are you messin' with me, KB? C'mon. I mean, you do know what a derivative is, don't you? :confused:

Inhomogeneous first-order linear constant coefficient ordinary differential equation: cv + x^2 = dv/dx

Kleanbore
September 26, 2012, 11:38 PM
Energy vs. distance traveled (∆V w/respect to ∆x/∆t) is not a linear function-Energy equals force times distance.

481
September 27, 2012, 01:26 AM
Energy equals force times distance.

Um, yeah...that's great, but it doesn't address the question asked.

Certaindeaf
September 27, 2012, 01:35 AM
In a world of compromises, all men do.

2zulu1
September 27, 2012, 03:45 AM
FWIW, consider this;

Attempts to determine bullet effectiveness or assign Wound Trauma Incapacitation by assessing bullet kinetic energy are doomed to failure for two interconnected reasons:

1) damage is done by stress (force), not energy.
2) an indeterminate, but usually large, amount of the bullet kinetic energy leads to tissue stresses that are not large enough to cause trauma (especially in handgun loads).

Let's remember we are discussing fluid flow dynamics, not brake temperatures.

An expanding bullet with 1800 ft/lbs of energy raises the temperature of three pounds of water by 1F.

FWIW, I have both of these references, but I prefer the "Quantitative Ammunition Selection" book to MacPherson's WTI book. it's an easier read and the author does a great job of walking the reader through the mathematical equations needed if they wish to test their carry ammunition, factory or handloaded. Since I live in a very rural area, both of these books have assisted me greatly in determining bullet selection/caliber based upon potential four legged threats. Not any gel data for 38Super loaded with 357mag bullets. :)

Certaindeaf
September 27, 2012, 04:05 AM
FWIW, consider this;



Let's remember we are discussing fluid flow dynamics, not brake temperatures.

An expanding bullet with 1800 ft/lbs of energy raises the temperature of three pounds of water by 1F.

FWIW, I have both of these references, but I prefer the "Quantitative Ammunition Selection" book to MacPherson's WTI book. it's an easier read and the author does a great job of walking the reader through the mathematical equations needed if they wish to test their carry ammunition, factory or handloaded. Since I live in a very rural area, both of these books have assisted me greatly in determining bullet selection/caliber based upon potential four legged threats. Not any gel data for 38Super loaded with 357mag bullets. :)
So what focus does this work subscribe to? Are all projectile types held constant or is it just fuzzy numbers/math? If all projectiles are not the same type, it's still just begging the question/s.
Since you live in a very rural area, maybe just shoot prospects into some creek mud and go with that?

Kleanbore
September 27, 2012, 09:31 AM
The question asked was, "In a defensive rd for a handgun which is more important to consider....muzzle velocity or muzzle energy?"

At first glance, that seems nonsensical. Energy is a function of velocity and mass. But the discussion has flushed out more. Perhaps this will summarize things well enough:


In handgun bullets, energy is not an imprtant factor in determining wounding effectiveness.
The important factors are the following:



Where the bullets hit, and in what direction, in a 3D human target
Penetration
Bullet diameter


The first one does not refer to bullseye accuracy; the target is likely to me moving fast, and the defender will not have time to aim accurately, or to reliably make one shot hit where he or she would like, and rapid repeat fire is likely to be needed.

Penetration into a given medium is a function of velocity, mass, diameter, bullet shape, and bullet construction. It can be measured by firing into surrogate materials that are generally representative of human targets. Predicting the results of that kind of tests using the results of penetration in water has been done.

There is not a lot of difference between the diameter of an expanded .45 bullet and that of an expanded 9MM bullet. A .45 will generally have a lower magazine capacity and, in a firearm of similar size and weight, greater recoil, which will make rapid repeat shots more difficult.

It hasn't been discussed much in this thread, but some may not realize that boom, blast, and fuss at the muzzle does not translate into "knockdown power." There's really no such thing.

There is insufficient information available, and there are far too many variables involved, for anyone to draw any meaningful conclusions from the results of real-world shooting incidents.

Personally, I do not see the point in spending much time trying to decide whether the modeled or tested performance of one particular round is marginally better than that of another. Given reasonable published assurances that all of my choices meet minimum standards (I'm happy with FBI standards), I will base my choices on reliability in my handgun, availability, and price, in that order.

481
September 27, 2012, 10:05 AM
So what focus does this work subscribe to?

CD, You can read for yourself here-

http://quantitativeammunitionselection.com/the_book

copied/pasted from various parts of the website-

QUANTITATIVE AMMUNITION SELECTION presents a mathematical model that allows armed professionals and lawfully-armed citizens to evaluate the terminal ballistic performance of self-defense ammunition using water as a valid ballistic test medium. Based upon a modified fluid dynamics equation that correlates highly (r = +0.94) to more than 700 points of manufacturer- and laboratory-test data, the quantitative model allows the use of water to generate terminal ballistic test results equivalent to those obtained in calibrated ten percent ordnance gelatin. The quantitative model accurately predicts the permanent wound cavity volume and mass, terminal penetration depth, and exit velocity of handgun projectiles as these phenomena would occur in calibrated ten percent ordnance gelatin and soft tissue. With a confidence level of 95%, the model predicts the terminal penetration depth of projectiles in calibrated ordnance gelatin within a margin of error of one centimeter.

The book sure was a learning experience for me. :)

481
September 27, 2012, 10:35 AM
The question asked was, "In a defensive rd for a handgun which is more important to consider....muzzle velocity or muzzle energy?"

At first glance, that seems nonsensical. Energy is a function of velocity and mass. But the discussion has flushed out more. Perhaps this will summarize things well enough:


In handgun bullets, energy is not an important factor in determining wounding effectiveness.
The important factors are the following:



Where the bullets hit, and in what direction, in a 3D human target
Penetration
Bullet diameter


The first one does not refer to bullseye accuracy; the target is likely to me moving fast, and the defender will not have time to aim accurately, or to reliably make one shot hit where he or she would like, and rapid repeat fire is likely to be needed.

Penetration into a given medium is a function of velocity, mass, diameter, bullet shape, and bullet construction. It can be measured by firing into surrogate materials that are generally representative of human targets. Predicting the results of that kind of tests using the results of penetration in water has been done.

There is not a lot of difference between the diameter of an expanded .45 bullet and that of an expanded 9MM bullet. A .45 will generally have a lower magazine capacity and, in a firearm of similar size and weight, greater recoil, which will make rapid repeat shots more difficult.

It hasn't been discussed much in this thread, but some may not realize that boom, blast, and fuss at the muzzle does not translate into "knockdown power." There's really no such thing.

There is insufficient information available, and there are far too many variables involved, for anyone to draw any meaningful conclusions from the results of real-world shooting incidents.

Personally, I do not see the point in spending much time trying to decide whether the modeled or tested performance of one particular round is marginally better than that of another. Given reasonable published assurances that all of my choices meet minimum standards (I'm happy with FBI standards), I will base my choices on reliability in my handgun, availability, and price, in that order.

Great post.

Well, Kb, I'll say this- you and I agree about as completely as two folks can about the vast majority this stuff. I doubt that there is any significant difference between our points of view- even if you were messin' with me for a bit! :D

brickeyee
September 27, 2012, 02:48 PM
I'm not sure how billiard balls or punching bags relate to fluid dynamics,

Then you have a very limited understanding of physics.

Billiard balls are nearly 100% elastic collisions.
VERY little energy is lost.

A punching bag is at the opposite end, an almost 100% elastic collision.
The bag deforms absorbing the energy.

Human tissue is not exactly a liquid very amenable to simple fluid dynamics analysis in many cases.
It is NOT isotropic (uniform) in composition, strength, density, or much of anything else.
The fact that cells have a high concentration of water does not remove the other components that give them shape and form.

There is a reason we do not look like jellyfish.

Kleanbore
September 27, 2012, 03:24 PM
^^^

Good answer.

McPherson points out the complexity associated with the conversion of kinetic energy to thermal energy in what he calls "real" collisions. The real collisions were not fluid dynamics events.

But: and it hadn't occurred to me, by firing into water, he was able to greatly simplify things by using a virtually pure momentum transfer experiment in which energy transfer was insignificant. Correlation with (gelatin representatives of) real collisions was the next trick.

By the way, I never realized that it was an interview with McPherson I was watching when he set the record straight for those who had concluded from the movement of a target's head (through which the bullet had passed) that they could prove the direction from which the shot had come.

481
September 27, 2012, 05:56 PM
But: and it hadn't occurred to me, by firing into water, he was able to greatly simplify things by using a virtually pure momentum transfer experiment in which energy transfer was insignificant. Correlation with (gelatin representatives of) real collisions was the next trick.


Ya see, when you say stuff like this, it makes me think that you'd enjoy reading books like MacPherson's Bullet Penetration and Schwartz's Quantitative Ammunition Selection.

Skribs
September 27, 2012, 06:23 PM
Bullet design will affect greatly how much energy you need. Essentially, you want to make a hole 12-18" deep and have it go as wide as possible. Handgun rounds aren't going to have enough energy to create the kind of permanent cavitation you'll see from rifle rounds.

2zulu1
September 28, 2012, 01:58 PM
Then you have a very limited understanding of physics.

Billiard balls are nearly 100% elastic collisions.
VERY little energy is lost.

A punching bag is at the opposite end, an almost 100% elastic collision.
The bag deforms absorbing the energy.

Human tissue is not exactly a liquid very amenable to simple fluid dynamics analysis in many cases.
It is NOT isotropic (uniform) in composition, strength, density, or much of anything else.
The fact that cells have a high concentration of water does not remove the other components that give them shape and form.

There is a reason we do not look like jellyfish.
You're correct, I have a very limited knowledge of physics; but, I can accurately calculate bullet penetration in soft tissue based upon data obtained from a bullet captured in water.

Perhaps you can share with us your bullet penetration calculations based upon punching a billiard ball.
:)

MCgunner
November 14, 2012, 10:19 PM
Hydrostatic shock is not a reliable wounding mechanism at handgun velocities. Bullets moving slower than ~2,000 FPS do damage by crushing and tearing tissue directly contacted by the bullet. Yes, there is often some peripheral damage done by the temporary cavity, but again, that is not a reliable component with handgun rounds. Unless you're a Michael Courtney deciple, in which case reality isn't relevant...........

Velocity really doesn't matter, only in the energy equation. It is energy that matters and at 500 fps + or -, the ballistic pressure wave matters. No, it's not a "reliable mechanism" if the shot isn't accurate in the proximity of a major nerve network, but I've seen the results and seen actuall remote tissue damage from a bullet's pressure wave NOT involving nerve tissue, even from a 165 grain Keith style SWC fired at 1800 fps making around 1200 ft lbs ME. Animal was 80 yards down range, so energy was in the 700 ft lb range with velocity down to around 1400 fps near abouts. Ths was a lung shot behind the shoulder on a 110 lb whitetail doe that jumped upon being shot and went about 20 yards before piling up. Around 2-3 seconds max, maybe less, not more, from hit to death with a lung hit, no other vitals, just the lung.

That's just one instance. I've seen lots more from calibers like 9x19 +P on trapped hogs, enough to make me a believer in the 9mm as a self defense caliber. I like the confidence in having used the gun on something over and over and seeing the results.

But, you can't shoot something in the foot and expect it to be immediately lethal. You still must put the shot in the right place. Whatever mechanism works is the one I'll run with. If none are immediately effective, try again. You cannot count on one shot from a .338 win mag to stop a person. You have to put the shot in the right spot and then you'd better be ready for a back up.

I'm not sure what all this arguing over Fackler vs Courtney accomplishes in the real world. I carry what I carry because it's small enough to easily conceal and I have confidence in my ability to make a shot with it and confidence in the round to do the job. Don't need math to figure that out. :rolleyes:

ArchAngelCD
November 15, 2012, 03:36 AM
In a defensive rd for a handgun which is more important to consider....muzzle velocity or muzzle energy?
Neither, IMO ACCURACY is most important because the best bullet in the world traveling fast and hitting hard will do little to no good unless you make good hits. If it comes down to a few fps choose the ammo that's most accurate in your handgun.

Decades ago when bullet construction was poor a wide heavy bullet moving fast was necessary. With today's bullet technology a JHP bullet can be traveling as slow as 800 fps and reliable expand. ACCURACY is the key...

CraigC
November 15, 2012, 11:43 AM
Neither. Both are great excuses for shooters to turn off their brains. In the real world, where lead and copper meet flesh, it's far more complicated. What matters firstly, where the bullet lands. Secondly, what does said bullet do at a given velocity? Does it expand AND penetrate sufficiently, providing ample tissue destruction? Or does it just punch a clean hole? Or does it expand too quickly, yield a nasty, shallow wound? Unfortunately, there is nothing in a ballistics table or mathematical formula that will tell you the answers to these questions. Yet shooters remain obsessed with velocity and that most useless of all numbers, kinetic energy. :rolleyes:


If it can make a hole, reliably, deep into the important bits, that is what is most important.
The only thing that matters is what you put a bullet hole in.
Exactly!

brickeyee
November 15, 2012, 12:59 PM
I can accurately calculate bullet penetration in soft tissue based upon data obtained from a bullet captured in water.

Only if you want to pretend that the "soft tissue" is uniform and nothing else is present.

Like muscle vs. fluid filled organs, or even air filled organs (like lungs).
It just does NOT work and devolves into a waste of time.

You are free to waste as much time as you want.

There are simply so many variables that it is not possible a priori to tell what A bullet is gong to do in A target with an arbitrary path.

Skribs
November 15, 2012, 02:54 PM
I don't look at any of the numbers at the muzzle, I look at the numbers in the target. Bullet design will mean much more about what happens at impact than the muzzle energy. I look at test results - how far does it go, how wide does it get?

481
November 15, 2012, 03:10 PM
Only if you want to pretend that the "soft tissue" is uniform and nothing else is present.

Like muscle vs. fluid filled organs, or even air filled organs (like lungs).
It just does NOT work and devolves into a waste of time.

You are free to waste as much time as you want.

There are simply so many variables that it is not possible a priori to tell what A bullet is gong to do in A target with an arbitrary path.

Despite your insistence to the contrary, there are accurate models (in Bullet Penetration by Duncan MacPherson and Quantitative Ammunition Selection by Charles Schwartz) that predict the penetration of expanding and non-expanding bullets in calibrated ordnance gelatin which is meant to simulate the terminal behavior of projectiles in soft tissue so it is not without basis that such an application of these models can be made.

By way of example, Duncan MacPherson addresses on page 223 of Bullet Penetration, the validity of applying these models' yields to a projectile's terminal behavior in soft tissue given the problems associated with the employment actual soft tissue as a test medium-

These considerations lead to the conclusion that it is not practical to provide the level of empirical support for tissue penetration modeling that has been described in Chapter 8 for gelatin penetration modeling. The penetration model developed using gelatin testing is consistent with tissue penetration data; there is no reason not to accept this model as valid for tissue penetration, and no practical alternative if a penetration model is wanted.

For this reason, both models (as proposed by Schwartz and MacPherson) relying upon calibrated ordnance gelatin testing data as they do, are suitable for the prediction of the terminal behavior of expanding and non-expanding projectiles in calibrated ordnance gelatin and soft tissue regardless of the particular isotropism of either test medium.

golden
November 15, 2012, 06:34 PM
Duke,

If velocity is that important, then the 5.7 m.m. round used in the FN pistols and submachinegun would be top of the hill, but no police department or federal agency I know of is issuing one.
If energy was most important, then cops would be carrying .44 magnums or full velocity 10 m.m. pistols. Very few cops do and no agency issues them.

Recoil mitigation and an effective bullet are much more important.
A heavy non-expanding bullet can penetrate deeply, but may pass through a target with causing much damage. The deer may bleed out and an exit wound increases the blood loss and creates a more visible trail.
That is fine in deer hunting, it is not a good thing in a gunfight. Deer rarely are trying to kill you,

Velocity produces energy and energy is what tranforms a hollowpoint into an expanded hollowpoint and controls the amount of penetration, but so do other factors.

Hign energy is often achieved by raising the velocity of a round. To do that, pressure has to increase, so noise, flash and muzzle blast may also increase.
The noise and muzzle blast are factors that have worked against the .357 SIG round, which by all the accounts I have seen is a very effective round.

Recoil is also a big factor and for some persons, it may be huge. Recoil controls recovery time, you can improve training and the grip material, but recoil is hard to mitigate.

Is it more important to get a second shot fired into the target or possiblely a second target or do you need a more powerful round?

I have decided to stick with the 9m.m. +P or +P+ in most of my defensive pistols. I think it has enough power and the recoil is controlable in mid size and larger guns. In compact and mini-pistols, I would go with standard 9m.m.

I shot a RUGER LC9, a couple of months ago. It worked as advertized, but was so unpleasant to shoot, I decided not to buy one. I knew that I would not be able to practice with it enough to feel comfortable.

The same thing holds true in revolvers. Many agencies preferred heavy, hollowpoint .38 Special loads to much more powerful .357 magnum ammunition for issue to their officers.

Just my opinions.

Jim

2zulu1
November 16, 2012, 01:34 AM
Only if you want to pretend that the "soft tissue" is uniform and nothing else is present.

Like muscle vs. fluid filled organs, or even air filled organs (like lungs).
It just does NOT work and devolves into a waste of time.

You are free to waste as much time as you want.

There are simply so many variables that it is not possible a priori to tell what A bullet is gong to do in A target with an arbitrary path.
Being retired I get to choose how I "waste" my time, but thank you for caring. :)

Given your response, do you believe bullet designers use software to calculate how a bullet expands and are able to design it to perform to a designated penetration depth in soft tissue?

While I'm not as knowledgeable in physics as you are, given your self appointed status, I believe both MacPherson and Schwartz to be more knowledgeable on this subject than you. :)

mr.trooper
November 16, 2012, 10:53 AM
In a defensive rd for a handgun which is more important to consider....muzzle velocity or muzzle energy?

Neither. In a world where a .32acp FMJ can exceed 16" of penetration from a pocket pistol, and a .22LR can reach 12" of penetration from a 4" plinker, why would you be worried about velocity or energy?

Neither of those cartridges have very much of either one (velocity or energy), but a properly placed pill from either will shut someone down in an instant. So therefore, why would you worry at all about such things when you are using something more potent?

Any cartridge at all that can reliably reach vitals with a hollow point (9mm Mak on up) would be an acceptable choice, as handguns don't do any additional tissue 'shock' anyway - they poke holes in things and let the blood out. Unless they happen to sever an important nerve bundle in the process, they will all be poor stoppers.

If velocity is that important, then the 5.7 m.m. round used in the FN pistols and submachinegun would be top of the hill, but no police department or federal agency I know of is issuing one.

Just a quibble, but you didn't look very hard. The 5.7 pistol is currently issued to elite units by 19 foreign militaries. Here in the USA it is used by the US Secret Service as well as the Duluth GA police department and the Passaic county NJ SWAT.

The P90 sub-machine gun is in use by 45 foreign militaries. Here in the USA it is in use by the US Secret Service, ICE, Immigration, 9 local and state agencies including the Alaska State Troopers, and 5 SWAT teams around the country. At least one local LE agency issues the P90 to patrol officers as a vehicle weapon.

No, the pair is not as common as Glocks or the MP5, but they are out there and they do see real use. If you want to check my figures just zip over to wikipedia - the sources and citations for both of these weapons are very well developed and maintained.

golden
November 17, 2012, 04:15 AM
TROOPER,

Which agencies is it exactly that issues 5.7 m.m. pistols for street use? What military ISSUES ONLY THE Five-SeveN pistol WITHOUT also using the P90 submachine gun.

A round fired by the P90 is in a completely different class. As you mentioned, departments issue 9m.m. pistols and MP5 submachine guns. If they are the same, why issue both. Obviously, a round from the P90 is going to be more accurately delivered as well firing full automatic. You cannot compare apples and oranges.

You also mentioned a NJ SWAT team. I am talking about issue to street officers and detectives by a major department. Do you know any? I do not.
If velocity is so important, why then are not the federal agencies, state police, county and city LEO agencies not issuing GLASER SAFETY SLUGS as standard issue. Why are they not carrying a round like the French ARCANE ammo that sent a 9m.m. bullet at over 2,000 fps.

Velocity is not the end all, it is just one of the components.

Jim

brickeyee
November 17, 2012, 05:06 PM
calibrated ordnance gelatin which is meant to simulate the terminal behavior of projectiles in soft tissue
Do you understand what 'simulate" means?

the lazst time a block of ge;atimn (orimamce or tother0 attacked nyone i am sure you could calcluate how a ullet penetrated.

It is a MODEL.

ALL MODELS ARE WRONG, SOME MODELS ARE USEFUL.

There is NO model that is truly useful for determining the path, penetration, and effect of of a bullet through anything as complicated as human anatomy, let alone any other animal.

Even is you fired the same bullet at the same point on different people, you are unlikely to end up with the same result.

481
November 17, 2012, 05:32 PM
Do you understand what 'simulate" means?

Yep. Calibrated ordnance gelatin simulates the average density and strength of soft tissue. The result that calibrated ordnance gelatin (or a model that predicts terminal ballistic performance in calibrated ordnance gelatin) yields is a predicted average of what the bullet will do in soft tissue.

the lazst time a block of ge;atimn (orimamce or tother0 attacked nyone i am sure you could calcluate how a ullet penetrated.

Not sure what you are going for here.

It is a MODEL.

ALL MODELS ARE WRONG, SOME MODELS ARE USEFUL.

All models (like F=ma, mv=mv, etc.) have some degree of inherent error, but that doesn't mean that they are invalid if they aren't absolutely without error/uncertainty. The Schwartz and MacPherson bullet penetration models are relatively accurate and very useful. Just because they are not absolutely perfect does not mean that they must be discarded.

There is NO model that is truly useful for determining the path, penetration, and effect of of a bullet through anything as complicated as human anatomy, let alone any other animal.

Even is you fired the same bullet at the same point on different people, you are unlikely to end up with the same result.

The MacPherson bullet penetration model (n = 400+, "r" and MoE are not stated by MacPherson) and the Schwartz bullet penetration model (n = 700+, "r" = 0.94, MoE = 1 cm) accurately predict the behavior of bullets in calibrated ordnance gelatin which produces results (expansion, terminal penetration depth, etc.) that match closely those produced in human bodies.

It is hardly a great leap to model this sort of behavior in predominantly isotropic mediums like ordnance gelatin- it is done all of the time in related fields like aero-dynamics and fluid dynamics.

Shawn Dodson
November 19, 2012, 10:56 AM
Do you understand what 'simulate" means?

the lazst time a block of ge;atimn (orimamce or tother0 attacked nyone i am sure you could calcluate how a ullet penetrated.

It is a MODEL.

ALL MODELS ARE WRONG, SOME MODELS ARE USEFUL.

There is NO model that is truly useful for determining the path, penetration, and effect of of a bullet through anything as complicated as human anatomy, let alone any other animal.

Even is you fired the same bullet at the same point on different people, you are unlikely to end up with the same result.

Properly prepared and calibrated ordnance gelatin provides an engineering evaluation tool to test JHP handgun bullet penetration and expansion performance in a realistic soft tissue simulant. In a defensive scenario, all of the VITAL tissues that we're trying to damage are ALL soft tissues. JHP bullets are designed to expand in soft tissues. A modern JHP handgun bullet recovered from a body closely resembles the same bullet that has been tested in ordnance gelatin.

Reliable rapid incapacitation is caused only by what vital structure(s) a JHP handgun bullet comes into direct contact with and how much damage it produces to that structure (wound severity). TYPE of tissue and AMOUNT of damage are what's important.

fastbolt
November 19, 2012, 02:17 PM
There was a day, when I was a younger shooter, when I paid close attention to the listed MV & ME.

In subsequent years I paid much less heed to such things, preferring to focus on weapon reliability with various ammunition, maintenance ... and my ability to put hits on an intended threat target in an effective & timely manner.

Nowadays I can also look for better hollowpoint designs for use as dedicated defensive ammunition, too.

As long as the loads keep the bullets running in the optimal velocity window for them to function as intended, regardless of barrel length (full-size, compact, subcompact, snub nose, etc) ... I'm free to focus on the weapon & shooter influences.

I see the shooter influences (mindset, training, practice, employment of tactics, etc) as the arguably more critical influences, anyway.

So ... ballistics? In a handgun? Sure. Suit yourself. Just don't let it distract you from the more critical considerations.

fastbolt
November 19, 2012, 02:19 PM
DT ... :eek:

otasan56
November 20, 2012, 10:41 AM
to establish bullet effectiveness. My 9x19 115gr JHP gives 400 foot-pounds of energy, and this is pretty good for a 9mm. ;)

brnmw
November 20, 2012, 12:59 PM
There is a loaded question... get ready for the slug fest! (If it has not started already that is.)

481
November 20, 2012, 01:01 PM
Properly prepared and calibrated ordnance gelatin provides an engineering evaluation tool to test JHP handgun bullet penetration and expansion performance in a realistic soft tissue simulant. In a defensive scenario, all of the VITAL tissues that we're trying to damage are ALL soft tissues. JHP bullets are designed to expand in soft tissues. A modern JHP handgun bullet recovered from a body closely resembles the same bullet that has been tested in ordnance gelatin.

Reliable rapid incapacitation is caused only by what vital structure(s) a JHP handgun bullet comes into direct contact with and how much damage it produces to that structure (wound severity). TYPE of tissue and AMOUNT of damage are what's important.

Well said.

Sheepdog1968
November 20, 2012, 03:33 PM
Hitting the target is by far the most important factor.

After that 38, 357, 44, 45, 40, 9 mm, 10 mm are all fine options.

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