quote:

Originally posted by SR4759:
An FMJ does not constitute a solid....

quote:

What we have then is;
(Pi x R³ x 4/3)/(2R x Pi) x Density = 2R²/3 x Density where R is the radius.

(Pi x R³ x 4/3)/(2R x Pi) = 2R²/3

quote:

2. All four spheres have the same sd.

quote:

GSC-HV....an expanding softpoint made from one solid-integral component of copper.

NF-SP an expanding softpoint comprising of a combination of different metals/components.

GscFN solid....comprising of a singular component, one solid monometal mass of copper.

WL-FMJ RN-solid....comprising of a lead core encased in a steel FMJ.

quote:

Originally posted by ALF:
We often see this term "work" pop up in discussions that has to do with ballstics.

I would like to hear what everyone here thinks Work means or what it is and what they believe it's reationship is to mass, velocity, force, momentum and heaven forbid SD ?

And how does that apply to the creation of a wound? After all this is what it's all about ?

quote:

Originally posted by SR4759:

quote:

Originally posted by Whitworth:

quote:

Originally posted by SR4759:Sorry you do not comprehend Gerard,
But solid means solid- not a composite of various metals.

Uh, no, Gerard fully understood and correctly answered. A solid is basically a non-expanding bullet and not only a bullet that is monometal.

Perhaps you do not understand either.
An FMJ does not constitute a solid....

quote:

quote:
What we have then is;
(Pi x R³ x 4/3)/(2R x Pi) x Density = 2R²/3 x Density where R is the radius.

(Pi x R³ x 4/3)/(2R x Pi) = 2R²/3


unfortunately there is an 'oops' in there
the frontal surface area of the sphere formula should be (2 x R x R x Pi)
and the rate of change of SD relative to radius of sphere reduces to 2R/3.

quote:

Originally posted by 303Guy:

Dang! I botched that one

quote:

So, the old saw that more sectional density, as a single factor, will give more penetration, has now been laid to rest?

quote:

Use in ballistics

…….

Within terminal ballistics, the sectional density of a projectile is one of the determining factors for projectile penetration. The interaction between projectile (fragments) and target media is however a complex subject. A study regarding hunting bullets shows that besides sectional density several other parameters determine bullet penetration.[2][3] Only if all other factors are equal, the projectile with the greatest amount of sectional density will penetrate the deepest.

References
1. ^ Bryan Litz. Applied Ballistics for Long Range Shooting.
2. ^ Shooting Holes in Wounding Theories: The Mechanics of Terminal Ballistics
3. ^ MacPherson D: Bullet Penetration—Modeling the Dynamics and the Incapacitation Resulting From Wound Trauma. Ballistics Publications, El Segundo, CA, 1994.

Jim
"Life's hard; it's harder if you're stupid"
John Wayne

quote:

Originally posted by ALF:
465H&H:


Our concern with bullets basically has to do with outcome, that outcome or desire for outcome has two applications.

Design to assure outcome and secondly , and likely the source of the majority of research the treatment of effects of outcome.

Without knowledge of how outcome is derived we are at a loss.

We can like many bullet makers proclaim in advertising that certain aspects of their particular design will be responsible for a specific desired outcome, hence their publication of certain data parameters.

Example:

They publish their values of SD of their products in tables in books or on the packaging of the box, the assumption or intent being that with knowledge of this data a user can be assured that that their product behave in a certain manner. The same applies to the publishing of kinetic energy as a value in a table.

What they omit to say is that this published SD may change if their bullet deforms or fragments or turns in the target. The same applicable to kinetic energy.... it's not the total energy thats important it's the instantaneous energy at the point of contact with the target and the amount of energy actually shed to the target thats at issue..... so publishing that data is actually a useless exercise when it comes to reality.

So if I were to use say a Sierra Matchking and a Barnes triple X and say one of these Cutting edge non con expanders the outcome would be the same because SD was the same or momentum was the same, when clearly they are not !

We can use a FN solid and a RN solid with same parameters and their behaviour and outcome is definetely not the same..... so why then the difference.

If static SD is the same, mass is the same and velocity is the same between the 3 examples cited why do they behave so differently.

The answer as some would contend is design and construction, which is in part true but from a physics point of view and purposes of description it boils down to dynamic SD and instantanous energy.

The effect of the reaction of the target in reaction to the behaviour of the projectile in question and its subsequent effects on the parameters cited is vastly different between the 3 examples cited.

Even if we use the same bullet same construction and vary only velocity and mass to give the same momentum the outcome differs.

So if we were to design a projectile from inception we need to ask the question to what purpose?

What is the desired outcome ? is this to be a Varmint bullet ? , is this for hunting elephant ? , or perhaps is this a bullet of war and the rules of engagement are dictated to by a convention of international law.

If for instance the purpose is projectiles with non lethal qualities to do crowd control with, then we have to know first hand what it takes to penetrate skin in terms of parameter values, we need to know how wounds are created and only then can we set about assuring a design that achieves the goal.

If on the other had we require highly lethal projectiles designed to take down a perp in a crowd without injury to innocent bystanders then again knowledge of the true nature of the wound production is a requirement. So we go on right down to munitions that give very deep penetration.

From a medical point of view we have applied treatment strategies on the one side and forensics on the other where the result of examination and analysis influences outcome in legal disputes.

In courts the correct interpretation of fact may mean the difference between guilty and aquittal in legal dispute. example: A common point of dispute whether momentum of a bullet has the ability to throw a body back when impacted.

In the field of surgical practice our treatment protocols are dictated to by the knowledge of etiology, it is after all a requirement under our ethical obligation as physicians.

quote:

Originally posted by 465H&H:


My question had to do with the use of an SD based on bullet diameter as opposed to bullet frontal area. Since they are linear, what is the advantage to using the frontal area in SD calculation and if so, why??

465H&H

quote:

Originally posted by ALF:
Sorry I misunderstood:

You are assuming that the projectile is symmetrical and that it meets its environment head on.And that Surface area A is a scaled fraction or multiplication of the original area described by circumference of the bullet as implied in the static SD value on the box.

But projectiles are not necessarily symmetrical nor do they present themselves as round discs. Oblong projectiles ( L>d)have this peculiar tendency to overturn in the target ie turn their side profile to the target some time during the process , others fragment either into discreet non symmetrical fragments or non symmetrical parts still attached to the body of the bullet. The fragments are even more peculair in that they turn side on and then remain in that position.

How do we account for these in absolute numbers?

The number itself is not important, but rather the implication of a low or high SD as an indicator of how much resistance the target is going to offer at that point in time.

The measure of that resistance showing as the volume of target material dsplaced by the passing projectile.

We see so often that someone says this bullet has a SD of so much and that one this much and therefore bad, or good ?

Yes pre impact SD numbers are only important and valid if the projectile remains intact, holds its posture and does not deform; and not to forget that there is sufficient velocity to actually support cavitation around the projectile. ( below 200 fps cavitation is no longer supported and the whole projectile surface becomes wetted.... we see this with arrow wounds when an arrow impacts a visco elastic target and the arrow is tipped with a target or field point. Once the arrow is removed the cavity collapses to a very small tunnel only.

Otherwise the exact number is of little value, not to mean SD as entity is not important.

The Important aspect of SD is that during penetration it links to momentum, because the mass fraction is in motion it has velocity and it interacts through that important surface area A . The resistance it meets is a function of velocity, not just velocity but the square of the velocity and that surface area A

quote:

Originally posted by ALF (Posted 01 July 2012 21:48):
And yet those who are promoting these bullets deny that SD has anything to do with it, there are some in the chorus who even proclaim that SD id old fashioned and somehow it does not apply to these new bullets..... The reason I suspect is that they rely on and apply the wrong definition.

In their thread they put SD low in the rankings when in fact is front and foremost in everything they do in design.

The fragments that are generated act just like a varmint bullet, low SD - high drag resulting in massive local energy transfer and thus potential damage as we see, the pictures posted on the terminal performance thread bear this out. (the logic however of showing something and them claiming it does not exist confuses me? you observe as shown by the pictures the effects of high drag caused by low SD and somehow then deny its existence.

quote:

Originally posted by ALF (Posted 01 July 2012 21:48):
Through design we manipulate the bullet parameters of mass, velocity and cross sectional area which in turn evokes a specific target response which in fact is the wound.

Jim
"Life's hard; it's harder if you're stupid"
John Wayne

quote:

Schoolboy 'genius' solves puzzles posed by Sir Isaac Newton that have baffled mathematicians for 350 years

Read more: http://www.dailymail.co.uk/new...s.html#ixzz1zU7Vr7jg

quote:

construction determines the reaction of the projectile in impact The physics determines what happens at that point & from that point onward.
You can only manipulate the reaction of the projectile to the penetration event , you cannot change the rules of the physics of the event.
You can't create mass, momentum or energy , you can only disperse it .
In a fragmenting projectile:-
Construction determines the susceptibility of the projectile to respond to the physics of penetration in a particular way
The physics describes both the dispersal event of the projectile into parts and the behavior of those parts whether its a CEB or a cup & core.
If the construction is not compatible with the physics limitations of the event, the event will not occur in the manner hoped for in choosing a particular construction.
Lots of variables affect the penetration event Whats immutable in the event is that the dynamic SD of the whole &/or parts determines the severity of the event and that it trades off penetration for severity of adjacent damage to the path of penetration of the whole or the parts.

Construction contributes to the event, but it doesn't determine the event, its physics that determines the event and its SD that is the pre-eminent driver of the physical event.

Jim
"Life's hard; it's harder if you're stupid"
John Wayne

quote:

Originally posted by ALF:
So being a keen follower of Shooting fashion I am keenly aware of the claims made by this and that "new bullet" or this and that new gun.

To my reasoning and correct me if i'm off base here if someone claims a product to be 'better than" then it means somehow or somewhere a test or head to head comparison was undertaken to serve as a basis for this claim?

So along came Gerard and his fine products, way before AR and there by virtue of being faced with what i saw as a failure of one manufacturers product I tried his bullets and they worked as advertised.

His HV's shot at high velocity really had a visible effect on animals when shot, it was someone literally pushed down on them form above.... the incapacitation was immediate !

As to this FN' that came later I do not think anyone could dispute that they too lived up to their claim.

Here on AR at least there was a love fest for these bullets.

Pages and pages of gloating praise for the conical flat . The very gods of AR proclaimed their worth!

Though sadly the reasoning given for why they worked often misrpresented by many even to the point of a reprint of bogus science in Pierre van Der Walts first edition on big bore cartridges.

There was even a direct copied reference to how these worked on Wikipedia untill, luckily for the sake of scientifc accuracy someone saw the errors and removed the whole article from wikipedia.


But something always bothered me, did success of one mean that the others suddenly did not work, by this I mean old style RN's and conventional cup and cores in their different presentations?

If so how come so many before had success with these ?

Many many animals fell before these old bullets ?

Many brave and famous men;

and really were they then so bad that one could not take them on a hunt?

And now suddenly a even "newer bullet" the "magic bullet" to end all other bullets,;

even the conical flat has been discarded for some new FN nose profile !

What I ask? : just yesterday these conicals were just the thing, now they are, well shall we say not so good ?

So were those who sang the praises of the conical flat right here on AR then wrong?

how could they be, could a finer bunch of descerning experts on matters hunting be so easily swayed by this new design ?

Again up pops the question in my mind......

if the new is better than the old how was the "state of better" determined

As "proof of evidence" an whole thread on AR is presented, multiple tests conducted using these new bullets ?
Observations claimed to support the findings in the tests.

This presented me with a dilemma because presentations are made regarding observations and conclusions derived in tests that do not test for question asked or the observation made in the first place.

it sound simple enough to take two bullets of different nose design fire them into a test medium compare penetration depth and then to claim one penetrates deeper than the other.

No problems so far ! no argument with the observed result.

But here comes the the kicker, the assumption and conclusion made that it is the nose design that is the cause of deeper penetration ?

This is in dispute because the test design does not directly test for nose profile alone...... it is assumed that it does but in reality it does not. One has to design a test that tests for nose design only and that is not so easy as many who do it for a living will attest to.

Nor the assummptions and conclusions regarding so called "trauma" to the test medium..... damage in the test medium does not equate to trauma is living tissue, damage to the test medium is a crude representation of temporary cavititation ie stretch, not necessariliy tearing !

But what is more bizarre is that a further coclusion is reached and that is that because of conclusion number one the one nose profile would be a 'better' bullet than the other, by this we are led to believe that one would be a better stopper of charging mice than the other ? The stopping of mice was never tested for!

Now I deal in medicine, every day new treatments are offered in place of the old. Just like our bullet thread, evidence is offered as proof.

The problem facing medicine however is that a burden of proof has to be presented that the evidence is in fact valid. That is how it works in the real world !

You cannot lay claim to " better" without proof that " better is in fact better" !

This, as anyone actually dealing with this small irritating, always in the way little detaille knows is not so easy.

In the real world do we slam someone for questioning the evidence, no! in fact we celebrate it, is that not what we claim to be? informed, wake up intelligent people who refuse to be taken..... on AR not so much.

You ask the questions and you get ousted and name called as some dumb ass .

Now does this mean I dismiss the whole thread as a whole? No! does this mean I think these new bullets do not work, Again no and finally do I have some agenda against those proponets of the tests or bullets absolutely not !

Jim
"Life's hard; it's harder if you're stupid"
John Wayne

quote:

Originally posted by ALF:

No where in the tests performed do I see a head to head test testing for lethality !...

...there are pictures of stacks of paper shot to a pulp and pictures of dead animals.....

...There are plenty of pictures of dead animals right here on AR not shot with these bullets and yet they are stone dead...