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The use of Sectional Density
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Posts: 7857 | Registered: 16 August 2000Reply With Quote
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SR4759,
quote:
Tell us how solids are constucted differently?
It seems that you truly do not know. Not your fault, you need more input. Example: Solids can be constructed from a copper clad steel cup, filled with a bonded lead core. Some solids are constructed from a copper alloy cup with a lead core. Solids can be turned from a variety of alloys or from pure copper, and so on. The same applies to softs and there are examples of these different construction types below.

A bullet with a high BC and no sd is of course impossible, regardless of how it is constructed, so you might want to rethink that question and ask again.

Copper clad steel jacketed, lead core solid


Brass solid, broken in half


Turned copper solid, with a coated finish.


Nosler Partition soft, constructed from a copper jacket with a front and rear compartment, both filled with a lead core.


Barnes TSX soft, constructed from copper by pressing and turning
 
Posts: 2848 | Registered: 12 August 2002Reply With Quote
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quote:
Originally posted by ALF:


Is this non- conventional or new ? can we really call these non con bullets?



The "non con" is not all that non conventional or new in principle.

CEB bullets loose their forward section[petals] at predetermined vel. and have increased penetration as result.

Nosler Partitions can also loose their expanded front section ending up with a reduced cross sectional area, thus also increasing its potential for greater penetration,...whereas a bonded A-Frame will maintain more of its expanded front section dia.
.... so you could have a lighter weight NP[lost nose section] penetrating deeper than a heavier retained weight A-Frame.

The mono-CEB and cup core-NP operate around the same principle, despite being differently constructed.

Its difficult to avoid marketing hype terminology like;

-"Hydrostatic" shock,...when fact it would be hydrodynamic, if any such shock actually exists at all.

-"Drive Band"[bullets],...when infact just about any hunting bullet that is not saboted, is a drive band design.

-"non con",...not as non-con as some would like us to believe.
 
Posts: 9434 | Location: Here & There- | Registered: 14 May 2008Reply With Quote
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ok, how about this? 308 win, 130gr tsx @3100 fps vs 300 rum 180 tsx @3100fps. Which will penetrate med game out past 300 yards, and why?
 
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quote:
Originally posted by eny:
ok, how about this? 308 win, 130gr tsx @3100 fps vs 300 rum 180 tsx @3100fps. Which will penetrate med game out past 300 yards, and why?

If you look at the terminal performance threads you can see the 130 grain CEB Raptor take on large African game at distances over 300 yards.


577 BME 3"500 KILL ALL 358 GREMLIN 404-375

*we band of 45-70ers* (Founder)
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Posts: 27614 | Location: Where tech companies are trying to control you and brainwash you. | Registered: 29 April 2005Reply With Quote
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quote:
Originally posted by Trax:
quote:
Originally posted by ALF:


Is this non- conventional or new ? can we really call these non con bullets?



The "non con" is not all that non conventional or new in principle.

CEB bullets loose their forward section[petals] at predetermined vel. and have increased penetration as result.

Nosler Partitions can also loose their expanded front section ending up with a reduced cross sectional area, thus also increasing its potential for greater penetration,...whereas a bonded A-Frame will maintain more of its expanded front section dia.
.... so you could have a lighter weight NP[lost nose section] penetrating deeper than a heavier retained weight A-Frame.

The mono-CEB and cup core-NP operate around the same principle, despite being differently constructed.

Its difficult to avoid marketing hype terminology like;

-"Hydrostatic",...when fact its hydrodynamic.

-"Drive Band"[bullets],...when infact just about any hunting bullet that is not saboted, is a drive band design.

absolutely false-most cup-core bullets are groove diameter and engrave.

-"non con",...not as non-con as some would like us to believe.


refers to non-conventional material and design, not concept


hence yes the appellation Non-con is appropriate for the new bullets.

coffee

SSR
 
Posts: 6725 | Location: central Texas | Registered: 05 August 2010Reply With Quote
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quote:
Your statement would only be true if you assume SD to be defined as SD = m/A ie a static value.

Yes. And Sectional Density IS a static value, that's all it is or ever was and your formula is correct. Note there is no way to inject velocity, flying sideways or any wet orthapeidics into it.

Estamating penatration was the single reason for the concept of Sectional Density for bullets. But bullet construction is so varied today that computiong SD is worse than meaningless about how a bullet will penatrate because, if used as intended, it's badly deceptive. And bothering to calculate or look up something meaningless is a waste of potentially meaningful time!
 
Posts: 1615 | Location: South Western North Carolina | Registered: 16 September 2005Reply With Quote
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quote:
Originally posted by Jim C. <><:
quote:
Your statement would only be true if you assume SD to be defined as SD = m/A ie a static value.

Yes. And Sectional Density IS a static value, that's all it is or ever was and your formula is correct. Note there is no way to inject velocity, flying sideways or any wet orthapeidics into it.

Estamating penatration was the single reason for the concept of Sectional Density for bullets. But bullet construction is so varied today that computiong SD is worse than meaningless about how a bullet will penatrate because, if used as intended, it's badly deceptive. And bothering to calculate or look up something meaningless is a waste of potentially meaningful time!


bsflag

Alf is absolutely, scientifically correct in all he asserts.

SD is indeed the basis of internal ballistics, inside the chamber and bore of a firearm, or any adiabatic, internal combustion engine.

SD is indeed the basis of external ballistics, "it drives the BC."
A pointy feather has very poor BC.

SD is indeed the basis for terminal ballistics,
it does indeed drive bullet penetration,
and it drives bullet expansion.

The only problem here is need of an attitude adjustment.
I believe ALF has crossed the bridge from the old to the new rules.
SD is still of prime importance, but so many other factors
(as listed by michael458 on his "Terminal Ballistics" thread in Big Bore forum)
are at play here,
that we all just need to be more accepting of a .2 SD instead of .3 SD,
as long as the bullet material and design are up to the task.
Yes, greater penetration by higher velocity sometimes happens.

I thought it was great that ALF took Terry Wee-wee-Land to task.
Somebody needs to get Terry out of Nostalgia Land.
ALF is a great resource.
I truly think he has the patience of Job in dealing with us bubbas in need of some education.

Thanks ALF.
Just quit deleting your posts, please. wave
 
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quote:
SD = m/A ie a static value.
 
Posts: 1615 | Location: South Western North Carolina | Registered: 16 September 2005Reply With Quote
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The old rule is still the new rule.
Its an immutable physical dynamic that has not changed since it was first described.

SD=m/A is a description of a physical dynamic
its not a static value
It describes what happens to SD when you change "m" &/or "A" in the object.
It also describes the SD of fragments of the object.
Its just a description of a physical dynamic.

He He..... the 'attitude' change thats required is simply recognition that SD never told you everything that you needed to know about penetration.
It was a simplistic concept that many interpreted beyond its real value as a predictor.

That interpretation just got harder over time as more diverse bullet constructions were developed.

bullets of the same weight, calibre , cartridge & load always behaved differently in penetration relative to SD between manufacturers since the time the first brass case was loaded.
It was just that the differences in projectile construction and mushrooming (changing "A" in the SD formula) between manufacturers at the time was small........... so the difference in dynamic change in SD after impact was small ........so the gross effect of different SD of the projectiles ( printed on the packet) dominated correlation to penetration.

projectiles with more diverse construction and types of materials just widened the gap between SD on the packet & the actual penetration.

whether the projectile :-
- fragments at impact
- deforms at impact
- retains shape
- partially fragments & the rest retains shape
- or skews relative to its direction of motion.
the projectile and/or parts of the projectile still obey the same SD dynamic described way back when.

Its our thinking about how some of us apply the SD dynamic that needs to change .The physical dynamic hasn't changed , its the nature of what we are applying it to that has changed, because we have projectiles that behave differently to the "old" days after impact, as a result of their construction.

Same as the dynamic of the projectile sealing the bore :-
- classic cup & core
- banded
- grooved
The dynamic of sealing is still the same, the rifling is just engraving more or less material.
The classic cup& core just engraves more than it needs to to either seal or drive the projectile rotation.

We still make'em as cup & core because its cheaper to manufacture & the penalties of that construction on performance traveling down the barrel are not huge.
The sealing dynamic has not changed with different hunting projectile designs, all thats changed is the way we design the shape of the projectile to use the same dynamic to our advantage.
 
Posts: 493 | Registered: 01 September 2010Reply With Quote
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quote:
projectiles with more diverse construction and types of materials just widened the gap between SD on the packet & the actual penetration.

Exactly so.
 
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quote:
Originally posted by Cross L:
quote:
Originally posted by Trax:

-"Drive Band"[bullets],...when infact just about any hunting bullet that is not saboted, is a drive band design.

absolutely false-most cup-core bullets are groove diameter and engrave.



Hunting bullets old and new [cup core or monometal] are barrel groove diameter that engrave.
Its just that some later bullet designs reduce the contact area of the bullets outer dia. for reduced friction and reduced pressure...some more than others. e.g.;

Nosler Partition or Nolsler E-tip both have one large drive band outer surface of barrel groove dia. which engraves in the barrel,
The BarnesTSX has reduced driven band contact area [via the use of grooves] resulting in multiple drive-bands that engrave.
A GscHV reduces the width & surface contact area of it drive bands even more than TSX, so much that you can safely load the GSCHV against the lands, yet the gscHV drive bands engrave in the barrel just like the outer dia. of a Nosler Partion,E-tip or TSX does.

GSCustom-HP 225gn .338cal ..vs.. GSCustom-HV 225gn .338cal

The above GSC HP and HV bullets are both designed for use in barrels of the same bore and groove dia. specs[.330" and .338"]

Regardless of one(HP)having a singular[large contact surface area] drive-band and the other(HV) a multiple narrow drive-band comfiguration,
..they both remain a drive-band design bullet....with the multiple DB-"HV"[reduced contact area] version, offering certain advantages in regards to friction & pressure reduction and muzzle velocity increases.



quote:
Originally posted by Cross L:

refers to non-conventional material and design, not concept


hence yes the appellation Non-con is appropriate for the new bullets.

coffee

SSR

I don't know where you get your information from but,
Reading the B&M website it seems to me that it refers to Non Con as being an operational/working concept.


[QUOTE] We call them "Non Cons" for a reason, they are totally "Non Conventional". They work in a different manner from which our conventional expanding bullets work, Swift A, Woodleigh, Hornady, Nosler, all of our premium and non premium lead core jacketed bullets....


What exactly is a "Non Con"?

Non Cons can come in several different configurations, some I am only now discovering. A solid copper hollow point that has 4 or 6 blades/petals that peel back and shear off as it penetrates, a solid brass hollow point, same configuration that does the same, petals or blades shear off during penetration. I will explain this just below in detail. Another one that I recently lumped in the Non Con category is the North Fork Expanding Cup Point.

OK now you say "Michael is Nuts", we just got through saying that anytime a bullet starts to break up or loose weight, we take a chance of not getting enough penetration, and now he is saying that's exactly what some of the Non Cons do? This is where we leave our "Conventional Teachings" and get outside the box.

Let's start with a Copper Solid Hollow Point, much like the HPs I have been getting from Lehigh/SSK for the last few years. Hollow Point copper solids with 6 blades. As velocity increases these blades tend to shear off during terminal penetration. They are long blades, about 1/2 inch, they tend to want to hang onto the main bullet, copper is more malleable than brass, so these shear along the path of the wound cavity, causing massive trauma within the wound cavity as they shear. The remaining slug then becomes a large flat nose solid, and continues to penetrate, deeper as the petals shear. So, as the bullet looses weight, as the petals shear off, "Penetration Increases"! It does not decrease--but in fact increases, destroying tissue that otherwise would have never been touched, increasing trauma and destruction of tissue.
[endQUOTE]

When a NP looses its expanded nose creating reduced cross sectional area for increased penetration,its behaving in non con manner...much similar to how copper or brass monometals loose their petals for increase penetration.

The NP does not adhere to "conventional teachings" much like the CEB do not adhere to them...of where a bullet is typically supposed to sacrifice penetration as it looses weight.
Clearly the NP,CEB,BarnesX and GSC can and do defy such old "conventional teachings" that Michael refers to.

Non Con bullet behaviour, if thats what you want to call it, is nothing new or revolutionary, numerous others bullets[both cupcore & copper mono design] were behaving in such manner, well before CEB came along.

Differing materials, design and construction, can significantly alter the minimum velocity at which the bullet will shed its nose section or petals and have effect on how long it will retain that mass after initial expansion.

Copper petals will bend way back and drag through while still attached, Brass HP bullets I believe will have its petals shear off at much lower velocity, and do not bend back and drag through like the petals on the copper HP bullets do.
I gather for greater penetration at particular lower velocities windows, the brass CEB would be the better choice.
 
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Alf,

THe bullet immediately after loosing it petals would indeed have less energy-momentum than [when just a micro second before] it still had all its mushroomed petals.

Although there is less momentum without the petals, there is also less resistance to penetration [less "braking" effect] in absence of the petals.

When I say "increased penetration" in absence of the petals I really should add, that such increased penetration is in trade-off for a smaller dia.[but longer] wound channel.

Alf, As you say, a bullet only has so much energy-momentum, which is ever decreasing after leaving the muzzle,
but with the different bullet materials,design and constructions available today,[combined with varying velocities] one can produce and reasonable predict and reasonably rely on particular/specific behavioral patterns from the bullet, in game.

FWIW, I have seen a .25cal 100tsx[3200mv]that lost its petals, penetrate substantially further than a .358cal 200gnNF[2650mv] that had way more initial momentum and might I say, way more parachute/braking effect with its fully retained mushroom....But if one[for some reason] needed or wanted a wider and shallower wound channel than what was achieved with .25cal,then the .358cal200NF would certainly be the better choice.
 
Posts: 9434 | Location: Here & There- | Registered: 14 May 2008Reply With Quote
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quote:
Originally posted by Trax:

When I say "increased penetration" in absence of the petals I really should add, that such increased in penetration is in trade off for a smaller dia.[but longer] wound channel.



All I would add there is that the wound channel of a brittle solid that has lost its petals as designed does a lot more damage in proportion to its diameter than a modestly larger diameter but typically rounded front mushroomed cup & core projectile.
The efficiency of the frontal shape of the projectile as it creates the wound channel in transferring the energy lost to what it is penetrating, sideways to the direction of travel , determines the extent of the width of the wound channel as well as the diameter of the object passing thru.

this is where the flatter face of a brittle projectile that has lost its petals & a softer monometal that has retained its petals , but has a concave centre to its frontal face have advantages in efficiency of transmitting force sideways than the classical rounded mushroom headed cup & core after impact.

The practical result is that they punch damage more than their diameter & velocity alone predicts.
Alf has well described the complexity of the dynamic in an object passing thru living tissue & the diverse parameters involved, in other posts & other threads.

Mass , velocity, & SD are major determinants but there are a bunch of other parameters in the dynamic that determines the actual penetration result & the extent of the width of the wound channel.

As hunters we want it all , we want width of damage & we want penetration depth , but we want that in the vitals & not so much in the meat...........its not a very tall order ..........He He.

The energy transfer dynamic unfortunately, strongly trades one for the other.
 
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quote:
Whilst I concede that SD is a mathematical designated entity in the field of physics and perhaps not a real tangible entity...

We finally agree! We are shooters/hunters and it's only the tangible things we are rightly concerned with. SD is a static quality originated to quantify some way to guess about penatration in game and so long as bullets were homogenous lead or cup and core it had some validity. That's no longer true, so calculated SD tells us nothing useful.

quote:
... it satisfies for now at least an attempt to describe the events that occur when a projectile in motion impacts a visco elastic ductile target.

We are not theoretical agonizers over esotoric minutiae. A "study" of SD in an attempt to understand trivia will interest some but it won't and cannot possibly resolve much. We KNOW initial energy transfer at the moment of contact is largely determined by area and velocity but that only makes a surface wound, killing penetration is then determined by the retained form intrigity of the projectial and mass that continues driving forward. And all that is determined by how well the projectile holds together and all that is determined by construction. SD tells us none of that so SD tells us nothing.


I've seen a formula for BC that included SD so a theorist has concocted such a method but I question the validity of it and the formula's existance in a book does not 'prove' SD has any real application to the question of BC, per se. I mean, adding the SD of a projectile without form factor while theorizing a method for calculating form factors seems a convoluted and disjointed approach, IMHO.

It's well known that computed form factors (BC) are unreliable anyway. The only valid way to determine BC is to do it on the range with two, or more, chronographs spaced some discrete distances apart, then using known speed changes over a known distance to calculate a BC for that speed does have meaning. But even then it's necessary to fire a series of shots at different velocities because BC changes with speed and no formula I've heard of can even approximate the changes in real drag at different speeds.

So, SD remains useless information for gunners. I think. But, if you can show how that little bitty, very simplistic static state SD formula can be made to include ANY of the factors you have cited into a dynamic event, I'll listen...until I fall asleep anyway! Wink
 
Posts: 1615 | Location: South Western North Carolina | Registered: 16 September 2005Reply With Quote
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Alf has taken a turn for the worse on this thread.
He is now feigning misinterpretation of Doc M's (michael458) explanations.
He has got to be faking it.
As smart as he is, there is no way he could misunderstand so badly.
Just creating an excuse for further pontifications?
It truly has devolved into mental masturbation, again, on this thread, if so.

Alf is also ignoring, or ignorant of, the real world terminal ballistic evidence offerred on
michael458's "Terminal Ballistics" thread, to be found permanently at the top of the "Big Bores" forum.
Still saying "wet pack" results are no indication of wounding potential on game, etc. ...
shame
Alf will do some reading on the "Terminal Ballistics" thread, I hope.
I hope he is just ignorant, and not dishonestly ignoring the real world results.

I am calling on ALF to educate himself.
Go look at the wounds on those animals taken with brass hollowpoint Non-Cons.

BTW: A brass Non-Con "soft" penetrates about half as deep as the brass BBW#13 solid of same caliber and similar weight and velocity.
There is a wicked increase of trauma in the initial portion of the shorter wound channel,
but no violation of the law of conservation of energy!!! Roll Eyes
 
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As someone who has worked in a number of fields of original research I agree completely with what Alf is saying about the adequacy of the test determining the outcome
The hardest part of research & testing is not the onerous work in the testing itself...........BUT making sure that the test design is not determining the outcome rather than the test measuring performance of a dynamic.

I think many are misunderstanding what Alf is saying
He is not anti- CEB or anything else & I have not read that into what he has said in this or other threads.
He is describing the dynamic of wounding as a result of projectile performance .
He is merely saying ( correctly) that the choice of test medium in part determines the outcome of the test on both the penetration result & the behaviour of the projectile in the medium............and that no test medium like gelatine or wetpack fibre truly represents living flesh ..........it is merely an approximation of living flesh .
and
We have to be careful in interpreting results in test mediums when we extrapolate test medium results into results on living flesh .

The bottom line is that the projectile responds to the test medium differently than living flesh ( the living flesh has more variability in it )
and
living flesh responds to the projectile differently than the test medium does.

The energy transfer dynamic strongly trades width of injury for penetration.

Its a little too easy to "over-hype" the
"Magic Bullet" that claims to defy physics and achieve both.

We can tweak performance within the physical dynamic , but we can't have it all, the fundamental physics will not allow it.

We choose the type of projectile construction that provides the type of wound we want and provides it within the variability of the medium it is impacting with an expectation of variation in outcomes depending on circumstance.
.........none of which is identified by the SD on the packet.

Fortunately for us the variability of the medium the projectile is passing thru between muzzle & target has relatively low density & variability so SD & BC are darn good predictors of behaviour in that medium.

We certainly did see over-hyping of performance & mythical behaviour of impact performance with the development of the military .223 in the Vietnam era.

He He ........that over-hying tho & the ACTUAL wounds did serve as a reality check on our perceptions of the physical dynamics at play and the treatment of the wounds ACTUALLY created
leading to a much better understanding of the reality.
 
Posts: 493 | Registered: 01 September 2010Reply With Quote
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quote:
Originally posted by Gerard:
SR4759,
quote:
Tell us how solids are constucted differently?
It seems that you truly do not know. Not your fault, you need more input. Example: Solids can be constructed from a copper clad steel cup, filled with a bonded lead core. Some solids are constructed from a copper alloy cup with a lead core. Solids can be turned from a variety of alloys or from pure copper, and so on. The same applies to softs and there are examples of these different construction types below.

A bullet with a high BC and no sd is of course impossible, regardless of how it is constructed, so you might want to rethink that question and ask again.

Copper clad steel jacketed, lead core solid


Brass solid, broken in half


Turned copper solid, with a coated finish.


Nosler Partition soft, constructed from a copper jacket with a front and rear compartment, both filled with a lead core.


Barnes TSX soft, constructed from copper by pressing and turning


Sorry you do not comprehend Gerard,
But solid means solid- not a composite of various metals.
 
Posts: 13978 | Location: http://www.tarawaontheweb.org/tarawa2.jpg | Registered: 03 December 2008Reply With Quote
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So what would you call the bullets in the first picture? Softs?
 
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quote:
So what would you call the bullets in the first picture? Softs?



Colloquially solids have meant non-expanding. Only since mono-metals have solids started to mean a single piece of metal, and not a non-expanding jacket over a core of lead or other metal. I think the vast majority regard solids still as non-expanding regardless of construction and further identify mono-metal solids within that definition.
 
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Uhhh... fasinating stuff guys, but the issue is Sectional Density. And the ratio of Mr. Bullet's weight to cross-sectional area is all that amounts to.

Everyone who knows anything knows bullet construction varies tremendously so what value is SD? Zip.nada/nothing! Smiler
 
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I would not say a bullets Sd value is entirely irrelevant or worthless, but it can certainly be given more importance than it deserves. A bullets particular material[s], construction and design should also all be taken into account....as should be the particular region of animal anatomy one is trying to penetrate.

Sd alone, may not necessarily be a true or accurate measure of a bullets penetrative capability, nor can one assume that a higher Sd will necessarily result in greater penetration.

Its pretty much undeniable fact that when using monometal SP bullets, one can go down a weight[or two] and still achieve the same [or greater] penetration than achievable with heavier weight-higher Sd,cup cores.



Finn Aagaard, extensively verified with his .30/06 that the Barnes 165x 2800mv, consistently delivered greater penetration than the 180NP, in game.
 
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He He
The non-expanding solid with a meplat of 70% or better has a better 'SD > penetration' correlation than than any other hunting projectile. IMHO

SD comparisons within that type of projectile is a reasonable predictor of penetration after impact, simply because if it stays together & doesn't change its frontal area ,its SD doesn't change during penetration after impact and energy transfer is dominated by other parameters in the dynamic that are less variable than SD change in a deformed projectile.
 
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BaxterB,
The question was aimed at SR4795. Bullets that are manufactured from a single piece of metal are called monometallic (monometal, mono) bullets. Such bullets can be softs or solids. Since bullets have been made, these have been the descriptions attached to them. So, there are cup and core solids and softs. Similarly, there are solid shank softs, solid nose softs, partition softs, coper clad, steel jacketed solids and so on.

When we speak about softs and solids, there is no confusion. It is the style of bullet that we are referring to, not how it is constructed. When we refer to the type of construction, soft and solid comes nowhere close to describing the variety of construction types and hence, are not used.

I would still like to know what SR calls the bullet in my first picture.

Alf, on page one of this thread, you post an illustration.
1. All four of the spheres are made from the same material, do not deform and impact at 2800fps.
2. All four spheres have the same sd.
3. As momentum increases, penetration increases.
4. What is the cause of the increase in penetration of the spheres? Momentum or sd?



Here is another excellent example:

This time we use two identical rifles. Rifle one is fired from the shoulder with only a primed case and rifle two is fired from the shoulder with a full load. The sd of rifle two is higher than the sd of rifle one by the weight of the charge and the bullet. The penetration of rifle two vastly exceeds the penetration of rifle one. Why is that?

 
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quote:
Originally posted by Gerard:


1. All four of the spheres are made from the same material, do not deform and impact at 2800fps.
2. All four spheres have the same sd .
3. As momentum increases, penetration increases.
4. What is the cause of the increase in penetration of the spheres? Momentum or sd?



G
rephrase required to 2.
ie
as SD increases, penetration increases.

The question is still valid........is it momentum or SD

Fuzzy head after birthday dinner out with the wife ( wife's), but it seems to me that SD is increasing at the rate of 2/3*r in increasing radius of the sphere

momentum/A is increasing at exactly the same rate.( C&F don't mention this in the schematic).
...........Good pickup G.

The experiment designer in me says that you cannot answer the corrected question you pose based on what is contained in this one experiment( Experiment 1 )
You have to tease out the answer from amongst the results of the combined tests.
............Which is why they are all listed together.

Experiment 2 looks at the effect of momentum
variation due to only velocity.
(penetration is inversely proportional to momentum).

Experiment 3 looks at the effect of momentum variation due to only mass
(penetration is a direct positive correlation to mass, SD & momentum increase from mass)
Experiment 4 looks at the same momentum but a change in frontal area
(penetration is a direct positive correlation to SD)

From those 4 tests you tease out that penetration ( of a NON-deforming projectile)
is a positive correlation to Mass per unit area
ie
penetration is proportional to SD.
- you exclude momentum from Experiment 2
- you exclude mass on its own from Experiment 4
By exclusion the only parameter that has a positive correlation to penetration in tests 1,3,&4 is SD.
Experiment 5 shows that a decrease in the dynamic SD during penetration from yawing reduces penetration as the increase in frontal area that dynamically reduces SD , increases drag......despite the projectile not deforming.
This again excludes mass alone as a parameter of penetration , as in experiment 4
( with experiment 4 examining higher & lower constant SDs & experiment 5 examining a decrease in SD dynamically during penetration).

Sorry Alf
couldn't help myself

these experiments represent a classical series of parameter isolation tests ...........classical textbook experimental design stuff to investigate a multi-parameter dynamic to identify the causative parameter of the effect that results from the dynamic.

Sorry too G for correcting your question to the dynamic identified in the test design in Experiment 1 & identified in the conclusion in that hard to read red stuff at the bottom of the schematic.

Ha Ha ..........this thread has me hooked , I come home after a dinner out & go straight to the damn computer to see what has popped up next.
 
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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.



"Ignorance you can correct, you can't fix stupid." JWP

If stupidity hurt, a lot of people would be walking around screaming.

Semper Fidelis

"Building Carpal Tunnel one round at a time"
 
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"terms of our current mathematical models of Newtonian mechanics and the extensions thereof denial of the existance or importance of the contribution of mass and cross sectional surface area in direction of motion leaves me and likely all of the current ballistics publications at a loss with regards to the description of the terminal ballistics event."

All the theoritical stuff aside, it's end effect we live with and few of us need charts and diagrams explaining the obvious for that.

How about you try, just in your mind, an SD experiment. I believe you are bright enough and know enough to do it fairly; consider the likely penetration of three bullets of the same diameter and weight (that is, having the same SD) and velocity into any medium you choose. Let one bullet be of thin jacket/soft core design, one of any controlled expansion design and one of monolithic construction. I think you know enough terminal ballistics to do that honestly so you know what the results will be. THEN you should see from your own knowledge that SD simply cannot give us any rational expectation of penatration potential from different bullets, which is the sole reason for the concept of SD. Meaning, SD has long been irrelivant for the purposes it originally served in a limited way.

Newton's mechanics may be good for fixing fig bars but he tells us little about modern bullets. Fact is, bullet construction means something, SD does not.

(Not that it matters to our discussion but, in my estimation, Mr. Newton was THE single greatest mental/scientific giant of history. And he was a committed Christian too! Smiler )
 
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quote:
Originally posted by DenisB:
quote:
Originally posted by Trax:

When I say "increased penetration" in absence of the petals I really should add, that such increased in penetration is in trade off for a smaller dia.[but longer] wound channel.



All I would add there is that the wound channel of a brittle solid that has lost its petals as designed does a lot more damage in proportion to its diameter than a modestly larger diameter but typically rounded front mushroomed cup & core projectile....

...The practical result is that they punch damage more than their diameter & velocity alone predicts.....


Indeed, the remaining x sectional area after loss of petals seems to leave one with a bullet that produces proportionaly more wound channel per unit of x sectional area.....a kind of increase in efficiency.

On the subject of efficiency, what impresses me most is the ability of an arrow broadhead to take game with only a small fraction of the velocity,energy and momentum that a HV centrefire hits an animal with.

You can hit an animal through the heart with a hyper magnum (3000fps-3500ft/lb)...and it can still run just as far as an animal hit by broaDhead through the heart.

However physical inspection of the heart would make ones mind think that the extra physical damage caused by the
HV-HE centrefire would make it the better more rapid killer.
 
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use of SD? its a measurement -- you can kinda compare like bullet shape and caliber to guess what it might do, relative.

but, like some dude telling me how much HP his car has... and looks poleaxed when i ask him "great, how much torque?"

HP doesn't actually measure WORK


opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com
 
Posts: 40016 | Location: Conroe, TX | Registered: 01 June 2002Reply With Quote
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quote:
Originally posted by Whitworth:
Uh, no, Gerard fully understood and correctly answered. A solid is basically a non-expanding bullet and not only a bullet that is monometal.


If you push some Softpoints fast enough through matter, it will become like a FN solid.

If you push FN solids hard enough through matter, they will show signs of deformation-expansion.

You can also design a solid in a way that it will expand somewhat easier than a FN and much less than a softpoint.
.... NF cup-point solid. ... and here.

[I would like someone to produce a mono metal CPS with pointy tip insert, that gives me long range BC advantage, but still behaves like a CPS on impact....in other words,I don't want it overly expanding and don't want it producing any major size petals that can sheer off.]
 
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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....
 
Posts: 13978 | Location: http://www.tarawaontheweb.org/tarawa2.jpg | Registered: 03 December 2008Reply With Quote
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quote:
Originally posted by jeffeosso:
use of SD? its a measurement -- you can kinda compare like bullet shape and caliber to guess what it might do, relative.

but, like some dude telling me how much HP his car has... and looks poleaxed when i ask him "great, how much torque?"

HP doesn't actually measure WORK


Yeah the hillbillies do not understand that their turbo charged diesel pickups run out of that torque above 80 mph.
 
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