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What are the two or three best artificial media for testing stability of a bullet after impact? By "stability," I refer to a bullet yawing in a different direction from which you aimed it. The best example of instability - that was planned for during development - is the original 5.56 mm military bullet to be fired from an M-16 with 1:12-inch rate of twist. Upon impact with people, the every-which-way that bullet traveled wreaked tremendous damage - but didn't penetrate well. Current 5.56 mm ammunition-rifle unit now penetrates well but is much less effective in terms of destruction on human beings.


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Posts: 1497 | Location: Seeley Lake | Registered: 21 November 2007Reply With Quote
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I respectfully disagree with your assertions regarding the effects of the 5.56 family of bullets.

However to answer your question.

In flight stability is best demonstrated by means of a doppler radar and high speed spark photography.

in target stability is best demonstrated by using a valid simulant like ballistics gelatine and high speed flash x-ray photography.

in both instances the setup requires a very expensive and dedicated lab type environment.
 
Posts: 7856 | Registered: 16 August 2000Reply With Quote
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shocker

Have you by any chance looked at the top discussion in this forum? Some 300 + pages
2020

it titled Terminal Bullet performance


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Posts: 3386 | Location: Central Texas | Registered: 05 September 2013Reply With Quote
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It's a great discussion but focuuses primarily on solid bullets. Since most of us don't hunt elephant regularly (unfortunately), the behavior of premium expanding bullets whether of mono or bonded / partition /a-frame construction would be more relevant to myself and probably the majority of the hunters on this forum


Regards,

Chuck



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Posts: 4729 | Location: Colorado Springs | Registered: 01 January 2008Reply With Quote
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quote:
Originally posted by Naphtali:
What are the two or three best artificial media for testing stability of a bullet after impact? By "stability," I refer to a bullet yawing in a different direction from which you aimed it. The best example of instability...


I am not sure that any artificial media can reliably predict the behavior of a bullet in the real world. Maybe shooting pig carcasses would be about the best comparison to a human or other large animal.
Also, there is really nothing that can be "built in", so to speak, to the bullet that enables erratic behavior during penetration which wouldn't disrupt the bullet in flight that I am aware of. Even making off angle alterations to the tip of the bullet doesn't have much of an effect on the flight or penetration path of the bullet in commonly used media. Saw that test in an issue of Handloader magazine about a year ago.
 
Posts: 3239 | Location: Colorado U.S.A. | Registered: 24 December 2004Reply With Quote
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The angle of attack ( defined as the angle between the long axis of the bullet and the tangent of the arc describing direction of motion ) greatly effects what the bullet will do in target.

The angle of attack at impact is a defining paramater in how long it will take for a ogived oblong non deforming non fragmenting bullet to overturn.

For years students of terminal ballsitics simply assumed that angle of attack at impact is small and thus could be taken as a small value ( calculations simply used a small number greater than zero as a arbitrary number) but a recent study actually measuring immediate pre impact angle of attack using current US mil issue M16 rifles and standard ammo have shown that there is a big variance in actual angle of attack at bullet gress from the bore and at impact.

The actual observed value is stochastic and will lie anywhere between zero and some degrees.

This exlains to some extent the differences observed in flight time from muzzle to target for a single rifle using standadised ammo and also explains why there is a variance in projectile behaviour especially at close range shots uisng a single rifle and standardised ammo.

The angle of attack at bullet egress from the barrel is stochatic again ranging between zero and and a few degrees.
 
Posts: 7856 | Registered: 16 August 2000Reply With Quote
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Given that very deep pockets are required for doppler radar, spark photography, x-ray flash and even for substantial amounts of ballistic gelatine, I think that the next best thing is to design for a particular reaction of the bullet in water and then take it hunting. Many animals are needed though and the trials may take several years. Water tells a good story as far as the bullet is concerned, especially if one uses witness sheets and it is a good place to start.
 
Posts: 2848 | Registered: 12 August 2002Reply With Quote
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Gerard:

In this lies the problem.

You take your gun, you fire the bullet into water, you retrieve the bullet and all you know is what your bullet looks like after the fact ! the same applies to shooting the same bullet into a stack of paper.

It tells us nothing about what happened to your bullet just prior to impact, during penetration up to that point where the bullet has come to a stop.

The water test is actually a very interesting one, because you fire your bullet with all it's energy, it penetrates the water, comes to a rest and absolutely nothing visible happened to the water !

There is no hole, just water, theoretically the temperature of the water has gone up and the potential energy of the water has also gone up because of the displacement of the water by the bullet now lying on the bottom of the pool.

But as far as we can see, nothing has changed.

The bullet may have deformed, fragmented or not but as far as a target reaction goes nothing seems to have occurred.

If you had a high speed camera recording the event you will observe a massive reaction, there is a splash, cavitation and wave formation, sometime quite violent ! the bullet itself may turn head over ass in the water but once it is all done, there is no change to the water.

And this is exactly why water on it's own can only be see as a bullet trap, no more no less, it tells us nothing about the bullets behaviour other than there may be deformation or fragmentation.
 
Posts: 7856 | Registered: 16 August 2000Reply With Quote
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Alf; Not trying to be a PIA but you always seem to just pass over the phrase "deep pockets!" If folks could afford the type of equipment you say is necessary to determine bullet performance I'm sure they'd just love to use it. In the meantime people use what they think is best for them and affordable. Then, of course, we have companies who can afford your preferred equipment but are not interested in determining performance of the bullets we want to use on game animals. So, my point is; "WTF is the medium you recommend that we, of far less than billionaire status, can use to confirm your theoretical musings about bullet performance?" You're very fond of saying "this won't work or that won't work" so what does work?
 
Posts: 159 | Registered: 05 August 2006Reply With Quote
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A7drvr:

Ok I get your point however:

How do you propose to observe directly or indirectly a event that takes place in fractions of a second, so fast the naked eye cannot see it ? or perhaps begin to understand what forces are at play ?

Yes you can guess and make up stories of what you think happened by looking at a bullet and pile of confetti blown out of a wad of paper but without concrete proof or actual observation you are sucking your thumb !

Now we have right here on AR 300 pages of just that. Not once and I mean this not once did anyone bother to ask or look at the science of what bodies in flight do ?


if you ask a airline pilot what makes their planes fly they can tell you, they can tell you about lift and thrust and how to make a plane stable.

It is far from theoretical !

Now we come to the question of the little M16 bullet ( or versions thereof)

The reality of it's function is locked up in the science of flight, it is locked up in the effects of how mass is distributed in that little bullet and what happens when you spin that little bullet' s mass around the centre of gravity..... exactly just like a plane in flight.

It is not theory it is reality though some refuse to acknowledge it and wallow between the flawed pages of flawed experiments done over and over.

Repeating a flawed experiment over and over does not over time make it valid, it remains flawed no matter how much you want to make it valid.
 
Posts: 7856 | Registered: 16 August 2000Reply With Quote
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ALF...If you know so much and everybody is doing everything so wrong, reach in your pockets put the cash down and show us. I'am sure everybody would love to see you spent your money showing us how you are right.
 
Posts: 424 | Location: Lk. St.Clair | Registered: 11 February 2011Reply With Quote
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quote:
Originally posted by Naphtali:
What are the two or three best artificial media for testing stability of a bullet after impact? By "stability," I refer to a bullet yawing in a different direction from which you aimed it. The best example of instability - that was planned for during development - is the original 5.56 mm military bullet to be fired from an M-16 with 1:12-inch rate of twist. Upon impact with people, the every-which-way that bullet traveled wreaked tremendous damage - but didn't penetrate well. Current 5.56 mm ammunition-rifle unit now penetrates well but is much less effective in terms of destruction on human beings.


Ballistic gel shows the path, at any rate...


_______________________


 
Posts: 4848 | Location: Clute, Texas | Registered: 12 January 2005Reply With Quote
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Coyote wacker:

Why on earth do you think I have to spend money playing games on something I know will not prove anything ? That would be plain dumb !

People make authoritative statements and come to conclusions regarding how bullets work based on "tests" that do not even test for the assumption made! Now that sounds harsh but that is sadly what it is.

if that is pointed out you and others get up in arms about it.

The premise of testing is at least that one formulate a question, then design a test or experiment to prove or disprove what is asked for.

The test has to test for a premise made.

Part of that process is to examine other tests , results and theories so as to limit bias.

So Naphtali here asks the question.

What medium would be appropriate to examine stability and penetration of various 5.56mm mil bullets ?

he then goes on and asserts that one bullet wreaked havoc and did not penetrate well and the other not ?

This confuses the original question because he has already answered his question based on what he thinks the cause of all this damage would be. Without actually testing for the question asked.

Now you do not need to spend a cent to test this, the military and others with the courtesy of your and my tax dollars have already done the testing for us.

The 5.56 mm military bullet is arguably the most tested bullet out there ! There are libraries full of test data on the subject !
 
Posts: 7856 | Registered: 16 August 2000Reply With Quote
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Should one be interested in the direction of the path in an artificial medium, water and witness sheets will do exactly that, without the expense of ballistic gel. To have ballistic gel experiments that are comparable from day to day, it has to be made to a rigid set of specifications that never vary. It takes more than one person to mind the process and a staff of several people is a good idea.

Water remains the same wherever you are on the planet. If you get 17" of penetration and a 3" veer over that distance, with a given set-up, you will see this in Atlanta, Boulder (pick one), Detroit, Glasgow (pick one) or Port Elizabeth, providing the set-up is the same.

As I have said many times, water serves only as a bullet trap and nothing can be learned from it, the same as wet paper, wet sand, dry sand, building blocks and other assorted building materials. The exception is, of course, if the object is to see how a bullet/cartridge combination works on the penetration of such material specifically.

To observe the terminal effect on game, nothing can substitute for live game. Water will teach us much about the bullet and it is repeatable and comparable.
 
Posts: 2848 | Registered: 12 August 2002Reply With Quote
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Good grief Gerard it's bad enough that we had to sit through 300 pages of wet paper testing now we are to believe water is the next best thing ?

Come on for a guy with your knowledge of bullets you really want us to buy into the water thing ?

This is exactly what I am talking about !

Someone wants an answer to a question about a certain aspect of bullet behaviour in the form of stability and damage done and water is offered as the solution?

We are dealing with Simulation here ! and in order for simulation to be valid the simulant has to by definition at least simulate one or more of the properties of the intended target you wish to simulate. Only data that are influenced by the properties of similitude can be taken as valid in the simulation test !

Water may have a density close to that of muscle but it has nothing else in common, it does not support shear, and leaves no "damage" there is no hole! nada nothing !

above all water is a FLUID and muscle is a SOLID!

There is absolutely nothing to be learnt from shooting bullets into a pool of water when it comes to the original question asked for !
 
Posts: 7856 | Registered: 16 August 2000Reply With Quote
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ALF; I think you missed the whole point of the wet paper bullet testing. Michael458 was not looking for theoretical BS about stability, shear, damage done, etc. He was looking at bullet designs that tracked straight through his medium and penetrated to the max distance. Does it infer the same results on "meat?" No, and Michael admitted that up front. His idea was to find designs that tracked straight and penetrated and then to try those bullets that performed best on actual game animals. You being of a scientific bent I can understand your disdain for practical testing, but how many bullets has all your scientific knowledge and dithering about it actually produced?
 
Posts: 159 | Registered: 05 August 2006Reply With Quote
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Alf, you should read posts and the questions asked therein, before going off half cocked and answering questions that were not asked.

Naphtali asked: "What are the two or three best artificial media for testing stability of a bullet after impact? By "stability," I refer to a bullet yawing in a different direction from which you aimed it."

Everyone stayed more or less on topic except you. You answered imaginary questions about external ballistics and methods that can only be attempted by a staff of people with unlimited funds.

I said very specifically:

"design for a particular reaction of the bullet in water and then take it hunting"

"Water tells a good story as far as the bullet is concerned, especially if one uses witness sheets"

"water serves only as a bullet trap and nothing can be learned from it"

Why do you keep on harping about holes in water and the reaction of water when we know all these things? I use water only to judge the reaction OF THE BULLET. It has nothing to do WITH THE HOLE IN THE WATER AND HOW THE WATER REACTS. Yes, I am shouting because you harp on this aspect incessantly, misunderstand and assume things that are not asked or said.

Ten years ago I said to you: "What happened? Did you pound out a reply after reading just the last sentence of my post in your haste to disagree and start an irrelevant discussion?"

It seems that it remains valid to this day.
 
Posts: 2848 | Registered: 12 August 2002Reply With Quote
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On a more serious note:

Many may or not know that there is currently a very credible and real threat to AR 15 type gun ownership in the form of the Obama Executive order that threatens a ban via the ATF on the sale of M855 Milsurp ammo ( Stanag designated SS109 ammo or US M855 ammo)

Now for years I have advocated that we collectively have real and truthful knowledge of how our bullets work and not rely on pseudoscience.... because sadly those taking aim at us are using science to fight us. In some instances of course distorted science.

The international drive that proposes a ban on small arms trade and movement have on their payroll and advisory boards of the worlds most imminent ballistics scientists. Looking at the Red Cross for instance they have literally to gods and gurus of terminal ballistics science on their payroll.

Unless we understand the science of how bullets work and what is credible science as opposed to what is junk we have no hope of fighting them !

What do I mean by distortion of science?

Distorted science is a imminent speaker at a surgical conference for trauma surgery standing up and giving a lecture on gun violence in the USA. Usually starting off reminding the willing audience of how many guns are in private ownership in this or that country and then somehow correlating that number to a high number of shooting incidents all of course with impressive tables and numbers.

Throw in a picture of some kid shot up distraught parents in the back ground and the message is clear.... guns are bad, guns killed the kid.

Then the call to arms, ban all guns period !

As if gun ownership has anything to do with gun violence.

I would on every occasion in question period remind the audience and the speaker that this is not science but a distortion of science.

There is no correlation between gun ownership and violence, in fact the opposite !

I remind them a gun has no will or itself and it requires the hand of a person to fire it. The reason for gun violence should be sought else where.....

The same now applies to the intended ban on M855 ammo.

Unless we truly understand how the little M885 62 gr bullet really operates and what its capabilities are we have no chance of taking the fight to the anti's.

The real danger is that once they ban a M855 bullet they can on the same premise ban each and every monometal bullet out there !

It is imperative that we as shooters fully understand what our bullets do and we have to be able to stand up in front of a court or law and be prepared to defend our position with true scientific knowledge !
 
Posts: 7856 | Registered: 16 August 2000Reply With Quote
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ALF; congrats! Your last sentence finally got to the point, at least partially. [Quote]"It is imperative that we as shooters fully understand what our bullets do"[Quote]

So, in your opinion what are the 2 or 3 best mediums for bullet testing by the unscientific mind? horse
 
Posts: 159 | Registered: 05 August 2006Reply With Quote
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The original poster asked what happens to stability AFTER impact. All this crap about in flight stability is prime example of a lack of reading comprehension, the desire to run up one's post count, or a shit stirring blowhard that wants to cause problems. Personally, I don't care if the bullet gets up on its feet and dances the watosi while in flight. What matters is directional penetration and stability which has been proven in Terminal Bullet Performance. For those that cry only solids, your lack of reading comprehension is showing again because expanding bullets from a few different mfgs were tested.


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Posts: 2973 | Location: South Texas | Registered: 15 January 2008Reply With Quote
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ALF, I'm wondering that too..
It seems after several posts you still haven't answered the question..? Confused Confused


You'll probably never NEED a gun. In fact I hope you never do. BUT IF you do, you will probably need it worse than anything you've ever needed before in your life...
 
Posts: 160 | Location: Melbourne, Australia  | Registered: 19 August 2013Reply With Quote
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There is no simple answer and I will explain why:

You have to ask yourself what is it you wish to simulate ?

Once you have asked that question then you will be required to know a little about what simulants are in terms of their mechanical properties and what each can do and what not !

ie will my chosen simulant answer the question i am asking of it when a bullet is fired into it. This is where science comes into it.

you pose the statement, assume the statment made is correct and then test to see if that statement is correct or an error. Assuming of course that the test was actually a valid one for the scenario.

This is sadly a science and not some simple backyard range acitivity.

It is costly requires some dilligence and for the most is too difficult to execute as a backyard hobby to be of value.

Lets assume we are to use properly prepared ballistics gelatine.

At 4 deg celsius a 10% solution will give us a mass density of about 1.03 to 1.06 kg / cubic meter which is for practical purposes the same as that of skeletal muscle.

So can therefore assume that a bullet fired into the gelatine would meet with the same resistance as muscle !

High speed photography has shown that the motion behaviour of the bullet ie tumbling, turning fragmentation and deformation is basically the same as in muscle.

So for study of bullet motion ballistics gelatine threfore is excellent as long as you have a accurate way of recording the event.

The accuracy of measurement of motion requires photographic or film recording with then measuring of angles against superimposed reference lines etc.

It also gives us acceptable values when looking at say penetration depth.

So in essence we can measure or look at certain bullet behaviours, we can accurately and with a certain measure of certainty derive valuable information about what our bullets will do, when shot into pure muscle. !

However It tells us little about living target behaviour ! Simply because the test is not designed to gauge target behaviour !


Many people make this mistake when looking a penetration tests in media and many bullet manufacturers erroneosuly ascribe target behaviours to the results of their gelatine tests. This is pseudo science !

Gelatine is however a problem substance to deal with, it is messy , temperature and age sensitive and in terms of visco elasticity is not very consistent.

To this end modern ballistics study have moved beyond gelatine to synthetic gels and kolloids.

But that is where it ends.

The consituitive behaviour of gelatine is elastic plastic with the majority of the behaviour falling into the plastic range, so whilst there is some bounce back to original shape a bullet fired into it leaves a large cavity.

This cavity is to some extent representative of the size of the temporary cavity but not sufficiently accurate to make determinations regarding wound volume or energy deposits.

Ballistics soap is better for this purpose.

Ballistics soap has almost purely plastic behaviour so its good to measure wound volume and make dedutions about energy losses. It is a poor simulant for the recording of motion phenomena.

Muscle on the other hand has elastic - elastic behaviour. Muscle is very special in that it is a living biomaterial that has some very interesting behaviours such as the ability to contract or relax at will or under command, it can heal itself over time and if we wish to study it from a enginering prespective we have some 9 parameters to deal with vs only two for say a beam of steel.

Ballistics gelatine is a poor simulant when it comes to measurement of energy losses.

Wet paper is a very difficult subtance to do anything with, nothing about paper has a similitude with muscle.

it is a woven composite solid and its behaviour to stress is very very difficult to model.

Stacked in layers, it poses huge obstacles to penetration stress , one simply needs to look at the enginering and paper science to see how difficult it is to punch a hole with a simple paper punch through a wad of paper.

Shooting bullets into paper is like shooting bullets into Kevlar, the principles regarding Kevlar fibre failure is the same as it is for paper fibre.
 
Posts: 7856 | Registered: 16 August 2000Reply With Quote
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Every hunter , police department , defence department asks the question:

Will my bullet reliably kill this or that animal or put down this or that perp or enemy soldier.
its a universal question !

The intuitive answer is shoot the bullet into a suitable simulant and it will give you the answer ? yes?

NO it does not !

The stimulant tells us what the bullet will do when shot into tissue simulated by the simulant.

it tells us nothing about how the target is going to react.

we can make some educated guesses and assumptions based on bullet behaviour in the simulant but actually testing for target behaviour...... that remains to this day the holy grail of terminal ballistics !
 
Posts: 7856 | Registered: 16 August 2000Reply With Quote
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So, after trying to mentally digest all of this, the only real conclusion to be made by firing bullets into gelatin, water, sand, clay, wet paper or ballistics soap is to see how it performs when fired into gelatin, water, sand, clay, wet paper or ballistics soap...
There really is very little which can simulate firing into a living being, only a basis of comparison to differentiate between bullet designs and compositions.
I have seen gunshot wounds, and generally, the amount of penetrated muscle is very little and there are many differing tissues the bullet will encounter and they all have different properties and have differing effects on the path of the penetrating bullet.
 
Posts: 3239 | Location: Colorado U.S.A. | Registered: 24 December 2004Reply With Quote
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Yes Huvius you are absolutely correct ! And those who study bullets and the effects of bullets wholeheartedly concur !

The two way street is very much alive and well in this discussion or exercise.

When looking at bullet behaviour we know everything about the actio side of the equation and can only guess about the reactio side. The actio side is tested for by simulation testing. We have little to test the reactio with.

We have no way of predicting why a buffalo with it's heart shot out can charge and kill you or why some guy survives what is seen as devastating wounds whilst another dies when shot with a little 22 cal revolver.

You will note when it comes to potential effectiveness of bullets in warfare the term probability and possibility enters into the equation and it becomes a exercise in statistics when it comes to the determination or choice of caliber and bullet.
 
Posts: 7856 | Registered: 16 August 2000Reply With Quote
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You can't really fully simulate an animal with test medium. But the behavior of a bullet in test medium can give you a pretty good idea of its performance in animals.

A bullet that blows to pieces in a few inches of gelatin or wet papers will blow to pieces in a few inches of buffalo and get you in trouble.

A bullet that consistently veers off course in test medium has no reasons to go straight in animal tissues.

A bullet that consistently holds its shape and trajectory in test medium will tend to perform similarly in animals.

Of course you can't fully predict what bone and other variables will do to your perfect shot, but comparisons between "grades" in test medium and in the field show a strong correlation.

Now, one can scratch his balls in front of a computer and keep on heaping scientific jargon to explain why it is not so, or he can go and spend one cent for each dollar, an hour for each day, and shoot and dissect one animal for each dozen of what has been spent and done by the likes of Michael and Gerard in designing and testing bullets. Once this is done, he may or may not come back with some real life data invalidating the works of those who have done that: work.

An essential ingredient of any healthy discussion is good faith, which seems to be sorely lacking in some posts around here.


Philip


 
Posts: 1252 | Location: East Africa | Registered: 14 November 2006Reply With Quote
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Phillip A:

Lets scratch some more balls as you put it:

You say X and Y are on to something by spending a cent, shooting something then dissecting it and then they are answering the questions asked?

Are they really answering the questions asked or are they scratching our balls ?

I am putting it to you that based on the complexity and the magnitudes of order at which ballistic events take place no amount of home dissecting etc will answer the question asked by Naphtali in the first place.

You can assume what you want but without real time observation and recording of the ballistic event you have no idea what happens.

By looking at a downed animal and standing with a bullet in the palm of you hand dug up out of the wound all you have are pieces of a after the fact puzzle.

For example:

Everybody speaks of this and that bullet being "stable" in a target, we have 300 pages of wet paper tests doing exactly that and yet something as small as a definition discredits all of that hard work.

It comes down to a simple word "stability" and how that is defined.

The definition of this simple ballistic concept derails the credibility of all the assumptions made and all the money spent.

When defining stability of a symmetrical body in flight 3 basic conditions have to be met, that is the conditions of static stability, dynamic stability and lastly tractability.

Gerard goes to long lengths to point this out and reminding us of the concept of a stability factor numbers and their importance.

However as soon as bullets enter the target these concepts are discarded or ignored.

The minute a oblong bullet (L>D) enters a dense target and transitions from air to the target it no longer can be defined as stable.

At least not if you accept the rules of play.

So speaking of a bullet being stable or having stable penetration is plain wrong. Yes we understand what they are trying to convey but they are going the wrong way about it.

Because by letter of definition the condition of static stability no longer applies ( you cannot maintain static stability because of the density differential of the target vs the air)

The Dynamic stability criterion goes out the window because that too cannot be met and finally all you sit with is tractability and by definition that to goes out the window.

So whilst your observation of one bullet tumbling head over arse and another not infers what people her call stable penetration in real physical terms is far from it. Going in a straight line and not veering, well that does not mean the bullet is stable it does by definition infer instability because going in a dead straight line means it is no longer tractable and it is also by definition dynamically unstable ( the yaw angle is growing over distance)

I can have tumbling bullet tumbling in a dead straight line or I can have a stable bullet as per definition stable doing what it is supposed to do, fulfilling all 3 stability criteria but veering because the path of a stable bullet in flight is in fact not a straight line it is a curved arc i.e. it veers.

A veering bullet in flight actually means the bullet is doing what we want it to do.
The definition of stability demands it to do so ?

Over distance it follows a arc shaped flight path and as result of our attempts to keep it on that path also deviates to one side. That is what is called stable flight ! if it goes in a dead straight line i.e. not following a curved path is it by definition unstable !

So a bullet going in a dead straight line in the animal and not veering is in fact unstable

Confused yet ?
 
Posts: 7856 | Registered: 16 August 2000Reply With Quote
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Alf

So if a rifle is zeroed at 100 meters and we compensate for bullet drop and shoot a kudu at 400 meters, then the arc is very much acute than when the kudu is shot at say a 100 - i.e. a flat curve. This then follows if the bullet must keep its trajectory path, and we shoot the kudu high on the shoulder, the bullet must exit low on the opposing shoulder, right? If this happens, then the bullet is stable by definition. If the kudu is shot 700 meters then the arc effect is even more so. With such an angle of attack we may now even encounter tumbling.

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Posts: 2148 | Location: Kirkwood | Registered: 14 November 2013Reply With Quote
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quote:
I can have tumbling bullet tumbling in a dead straight line or I can have a stable bullet as per definition stable doing what it is supposed to do, fulfilling all 3 stability criteria but veering because the path of a stable bullet in flight is in fact not a straight line it is a curved arc i.e. it veers.

A veering bullet in flight actually means the bullet is doing what we want it to do.
The definition of stability demands it to do so ?

Over distance it follows a arc shaped flight path and as result of our attempts to keep it on that path also deviates to one side. That is what is called stable flight ! if it goes in a dead straight line i.e. not following a curved path is it by definition unstable !

So a bullet going in a dead straight line in the animal and not veering is in fact unstable

Confused yet ?
Not really. All of us understand that bullets travel on arcs including wind drift.

That said, when a DG animal is shot at 25yds the computed trajectory over say – the animals 72” length – is not inches, it is tenth’s of an inch.
Here’s my example the JBM online ballistics calculator:
Sight Height 1.2” above line of bore
Zero = 25yds
500gr .458 Woodleigh FMJ @ 2150fps MV
Bullet trajectory from Line of Bore:
Zero yds = -1.2”
10yds = -1.3”
20yds = -1.4”
30yds = -1.6”
40yds = -1.9”
50yds = -2.2”
So over a 50yd path the bullet arcs -1.0”
However within that 50yd path there are ranges with virtually zero trajectory arc –
1yd through 16yds = -1.3”
17yds through 22yds = -1.4”
23yds through 27yds = -1.5”
28yds through 32yds = -1.6”
33yds through 35yds = -1.7”
36yds through 39yds = -1.8”
40yds through 42yds = 1.9”
43yds through 45yds = -2.0”
46yds through 47yds = -2.1”
48yds through 50yds = -2.2”

So looking at this – an indoor range with a 72” long bullet capture box containing wet newsprint – front of box at 25yds and end of box being 27yds should see the following bullet path trajectory =
Front of box at 25yds = -1.5”
End of box at 27yds = -1.5”
Way I read the JBM Ballistics trajectory path I should see a zero” deviation within the 2yd (72” long) bullet box from entrance to exit.
Therefore a bullet that enters the bullet box at -1.5” below the POA and exits the bullet box at -1.5” below the POA without deviation is tracking a correct ballistics arc. I’d also have to say the common individual would note this bullet track as straight-line penetration.
I’d also say that a bullet that enters the bullet box at -1.5” below the POA and exits one of the sides, the bottom, or the top of the bullet box has deviated the bullet path is tracking an incorrect ballistics arc.
But then I am a common person that tries to keep things simple…

Yes I reckon the bullet arc will be different when it impacts an animal at 300yds vs. 25yds but it still ought to be a very narrow deviation in the bullets arc between entrance at 300yds and exit at 300.5yds (presuming 18" wide animal) or perhaps 301yds (assuming a 36" wide animal) for a non-angled broad side shot.
Ok couldn’t help myself…
JBM online ballistics calculator:
Sight Height 1.75” above line of bore
Zero = 100yds
270gr .375 Barnes TSX at 2800fps MV
Bullet trajectory from Line of Bore:
300yds = -2.1”
301yds = -2.2”
Not much of an internal arc for the bullet; -0.05” over an 18” wide animal and -0.1” over an 36” wide animal assuming full-penetration and bullet exit.


Just sayin, an’t much after point of impact...


Jim coffee
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Capo

No sense in confusing their theories with facts.

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Fam. Trollidae, gen. Trollus, sp. Scientificus, ssp. pomposus

Splitting hairs multiple ways, with the only purpose being to argue for the sake of arguing while contributing little or nothing constructive to the general conversation...

Next time I shoot a buffalo at 1,200 m, I'll consult the relevant ballistic tables and dust my trigonometry. Meanwhile, being content with living in the open rather than in front of a screen, I'll stick with the traditional method of shooting big things close enough that a fraction of a millimeter this way or that way makes no relevant difference.

Knowing that a particular bullet works in a particular way does make a difference though, and this we only know from people reporting what they have tried and observed in real life - which is actually "repeatable experiment", open to anyone to confirm or falsify.

Provided the anyone in question is ready to put in some effort of his own, of course.


Philip


 
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Originally posted by capoward:

But then I am a common person that tries to keep things simple…
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