Hi Lutz,

I wonder if you would mind a couple of questions about your cavitator bullets.

First, I assume that the intent is to achieve deeper penetration and larger wound channels than we see with ordinary round nose bullets. Do you think that is achieved through the phenomena of supercavitation (i.e., encapsulation of the bullet by a vapor bubble as it travels through animal flesh)?

Second, I notice that the Cavitator bullet has a slightly raised center point as compared the flat meplats found on other flat nose solids. What function does the slightly raised center point serve?

Thank you!

Hallo 500grains,

the Cavitator Bullets take an Idea, first published by Norbert Hansen, see Hansen Superpenetrator, that he took from Russian Submarines. So the deserved Credit goes to Norbert Hansen, if not to some Russian Engineer in Tula or somewhere else.

All speedy Bullet push Meat aside, wet only in the Front (if stable) an the remaining Body sees only Water vapour (almost half Vacuum, or 0,61 atmospheric Pressure).This is not limited to so called Cavitator designs. Any Bullet penetrates like that. If the Bullet tumbles, the Front is simply somewhere else.

Penetration goes linear with sectional Density, less so with Speed, details see Poncelet.

Wounding, induced by Energy transfer, goes linear with Cross section (Fragments + Body) and square with Speed.

So for a not deforming and not fragmenting Bullet, to play with Body cross section, is a logical Step. Caveat! Do not forget Stability! Some Observations with Hansen’s “Supercavitators†on Buff on Others were quit cooling, as Bullet lost Stability, tumbled, then lost both Penetration and Direction too. Scary! As with most Superlatives, you then live on an Edge.

Contrary to the narrow minded “Super cavitorsâ€, singular raised toward Penetration, my Cavitator Bullet do mellow the Effect to suitable Dimensions down. After all, any Bullets Width, Length, and Meplat have to suit each other to yield a stable Bullet in the Target (Meat, Bone). Old, good Work by Fackler shows clearly how spitz Bullets tumble. The same could be shown for other Types, given certain Disturbance. These Dependencies are hard to come by with Numbers, and given the unknown Targets any Calculation is almost in vein, to accurately predict Behaviour.

Experience, sound Thinking and Anology helps to avoid Mistakes and stay within reasonable Dimensions, or Limits. To fully exclude an Error, when it counts (=before the Beast), Proof shooting must be done. On the other Hand, reasonable Designs won’t fail, so a good Design is worth to try, even in real Hunt.

The raised Center point, or Nipple, is just a Fashion, nothing serious, helps to memorize the Bullet (Your Notice just proved the Intent) and does not disturb the Function at all. Call it a Gadget, if You wish. A free Stream hitting a plane Surface yields hyperbolic Stream lines and ellipsoid Isobars.


Prandtl

Prandtl, the Father of all Stream mechanics, published the Equations back in the 20ties of the 19th Century. This is not new. You jus have to observe the Physics, to avoid Mistakes. Once You do it right, Things become easy. So pleas excuse my “Nippleâ€! I made I small enough to hide well in the Pressure Isobars outside an mentionable Flow, an large enough, to be noticed. I just like it. It’ s noting more.

LutzM

Lutz,

Thank you for the explanation. Have you recovered any from elephant or buffalo yet?

LutzM, that is the wrong answer.

Alf and others will shortly point out that the correct answer is this one:

"The center point, or nipple, if you will, is the unique, unmentionable, yet mellow, hyperbolic pressure isobar ellipsoid stream line defeating feature that provides the supercallifragilistic-cavitation qualities of this Lutz-Prandtl quit cooling bullet and renders it patentable."

Or words to that effect.

To which I and others would reply:

"Very pretty. But will they feed?"

All this makes me mourn for my baby's mama, Anna Nicole Smith. See me on FOX NEWS tomorrow morning at 7:17 a.m. for my admission.

JudgeG, to say that "you shouldn't have" might be a bit of an understatment... unless of course there were some Margaritas involved and a camera stragetically placed!

Definitely a perky design. Wonder what happens to it in the cold..

Seriously, the bullet is almost the opposite of a Northfork cup point. The cup point on a bullet actually leads to a slight expansion. Almost like something in between a solid and an expanding soft point.

I would be curious to see recovered bullets from large game. I have to believe there will be some difference between that and a solid.

Lutz, do you have a wedsite?

To digress, JudgeG is a man of great virtue. While there are many things that still surprise me in this world, a positive paternity test would not. Women take his kind ways as a sign of something different, forcing themselves upon him against his will. It is a curse few men know. For one victimized in such a manner, it takes a man of unique character to acknowledge paternity after being cruelly forced to surrender his seed. Yet, you will never, ever, hear him complain about these experiences. My hat is off to JudgeG.

http://home.snafu.de/l.moeller/

You mention the bullet in .577 Tyrannosaur on the website; do you have experience with this cartridge and bullet on game? If so, I'll send a PM to avoid throwing the thread off topic.

Hallo Mr. Lexma,

please take Look at the round Edge in the Front. The Edge in itself supports the Meplat, so it shall not expand. The Edges have certain Angle to not disturb Cavitation, or in other Words not to allow the Meat stream to laminate the Edge. Intends as a mild Cavitator such must be done.

If other Designers make different Bullets and use different Approaches, that is fine. Take a Look at Deformator and see a complete other Solution to a different Problem. None alone is better or worse, unless You specify the Goal and judge the Performance against it. The 14,5 mm Kavitator was designed to be shot out of a .577" T-Rex and give utmost Penetration. The Customer asked for a smaller Meplat for even deeper Penetration and i asked him if he wanted to shoot Whales in the Sea. You bet, next Day cam a Guy from New Zealand, asking just for that! I advised to allow some Margin for Stability and refrain to overdo the Concept and the Man listened. He just ordered another Batch, even longer and heavier.

He uses Competitors Bullets on Big 5 before, but had some Deliverey problems, so he shew up with me an ordered and I delivered within reasonable time Frame. If You were as greedy as he was to actually have them in his Hand, almost all time to wait was too long. But we managed to get everything done from first Contact to final Delivery in less than two Months (Couple of Phone calls and Emails in between).

Of Course I could use a harder Material to with stand the stagnation Pressure at 700 m/s Impact velocity, the Center Pressure in Meat is 245 Mega Pascal, or the Equivalent of a Water Column 245 m high! Copper starts to Yield around 245 N/mm², which is equivalent to this Pressure. This is the Reason for Copper. Lead yields already at 400 m/s impact Velocities and above 550 m/s just sprays itself into Dust, useless Dust in big game.

The Rifles Land engrave nicely into Copper and reduce Force, Friction, Heating, Fouling and Wear, if You wish, but that is no Problem at all in Big Five Rifle. Sure You can ruin a thin Barrel with on Shot with a too hard Bullet, but my Design refrain from that.

Arrow Tech Associates, Inc.
- Jeff Siewert -
1233 Shelburne Rd., Suite D-8
S. Burlington, Vt. 05403
Phone +1 - 802-865-3460 x19 http://www.prodas.com/ had some Tests done with conventional FMJ Bullets against my KJG. See the Pictures of an average of 40 Measurement Force against Way (through the Lead and Throat into the Barrel)





The conventional M80 FMJ Bullet exhibited 38% higher peak forces, than my KJG. Also look at the Sigma, the Standard Deviation. Here my Design really shines. A small sigma means, all Bullet bullets behave quite alike. A Large Sigma means, the measured Values spread. For this Reason (highly uniform Engraving forces) the KJG’s shoot rather well. Accuracy is no Point in Big Five Hunting, but if You go for Plain Game to, then You want it. The KJG delivers; usually from the first shot with the recommended Load right out of the Barrel. Low Engraving Forces and low Friction also mellow the Cold Bore Shot Problem from a clean Barrel. This is why I not really like Brass in the Barrel.

LutzM
p.s. I have no recoverd Bullet from Big five. I mostly sell into the German speaking Countries and have not had Time yet to cater for the English speaking Market. That would change, if I had a native English speking Salesmen.
p.p.s


These competitors "Cuppers" of cours can be made, but why? For which Purpose? Give me a ballistic Task and I will build You the Answer.

Kidding aside, the pictures are very interesting and of good quality. The bullet(s) look like they ought to be effective and I'd like to see some recovered "solids", too. Anything about feeding would be appreciated, also.

I gues what I'm saying is that I hope function follows form, 'cause they look wicked!

This will be a sad Valentine's Day.

Lutz,

I have found that a larger meplat leads to deeper penetration, so I am curious why your customer asked for a smaller meplat to achieve deeper penetration. Have you performed penetration tests with meplats of various sizes?

Jim,

you have got the judge all wrong! IMHO, and from what we read here, he suffers from the same potentially deadly illness as Bill Clinton...DSB*! I think the woman was trying to give the JudgeG some therapy, a sort-of Florence Nightingale if you will.

Rich
DRSS


* Deadly Semen Buildup

quote:

Lutz,

I have found that a larger meplat leads to deeper penetration, so I am curious why your customer asked for a smaller meplat to achieve deeper penetration. Have you performed penetration tests with meplats of various sizes?

Hallo 500 Grains,

Your Statement puzzles me! No I have not done these comparative Meplat size tests! I actually research Possibilities to build a Machine to do that easily, without resorting to Gelatine or Wax, as both are quite cumbersome to handle. Both take Time and make Dirt. Both I try to avoid.

But let’s come back to You Observation. Simple Physics would say, the Opposite is true, that means, from two equal Bullets with just different Meplats the one with the smaller Meplat should penetrate deeper. In Numbers the Penetration would be reverse to the Meplat Area.

Example: .416†Rigby

a) Bullet 15 g, Impact Velocity 875 m/s, Meplat diameter 9,5 mm, Meat Penetration 106 cm
b) Bullet 15 g, Impact Velocity 875 m/s, Meplat diameter 8,5 mm, Meat Penetration 132 cm

Now You say, this will not happen. If it does not, the simple Physics are too simple and some more Brain must be applied. Maybe the Bullets with the smaller Meplat are not stable. This could be easily found out by adding a thin Aluminium sheet in the Target every 10 cm or so. The Holes should be round. If Not, the Bullet tumbles.

High Speed Photography could be applied:



2 Micro second Exposure of Gases on a 8x68S Muzzle recoil Brake
(reduces Recoil impulse measured by 41%)

Unfortunately such Exposures take a bit of Work to get and are costly too. If someone would offer do certain Tests, photograph and document and allow the Findings to be published here, I would be willing to throw in needed Bullet specimen. We only can learn an by the Way comparative Testing would be welcome too! So Volunteers to the Front!

LutzM

Lutz,

A large meplat provides a larger supercavitation bubble which remains stable longer. A smaler meplat means the supercavitation bubble collapses earlier and penetration will be reduced.

My experience in the field confirms that a larger meplat provides deeper penetration.

Now I am getting curious. I have field experience, but it is with cast handgun bullets. I have hit an elk in the brisket with a 250 gn Keith 44 mag and it came out the hind quarter. About 4 1/2 feet of penatration.

I have used WFN in 480 Ruger on elk and bison and got less penatration.

What is your field experience with wide meplats..............JJ

MR: Doanld Sutherland in the "Dirty Dozen" right?

JudgeG: I think you have an affinity for large-breasted blondes my friend. jorge

quote:

A large meplat provides a larger supercavitation bubble which remains stable longer

I thought that supercavitation was something that only happens in water and not in flesh, being a "soft" solid. Did Alf not explain this notion/phenomenon at length, or was he not convincing enough? Lutz's theory stand in contrast to Norbert's theory in this regard, I think. It would be nice if Lutz could also explain to us again what forces are at work or the mechanisms at work of a bullet inside an animal.

Anecdotal evidence in game, where every shot differs in a variety of ways, cannot replace mechanical principles that say a .458"/11.63 mm bullet with a 10.5 mm flat meplat will out penetrate a 7.5 mm one, for example. Norbert Hansen did these test already when he experimented with his SuperPenetrator bullet.

I view Alf's explanation of bullet geometry and overturning moment as the best that I have seen so far ... "The distance it takes for an ogived non deforming bullet to tumble in target stands in a direct relationship to the ratio of the distance between tip and CG of the bullet and it's Transverse moment of inertia. This is an unchallenged ballistics fact."


Warrior

quote:

Originally posted by JJ_Miller:


What is your field experience with wide meplats..............JJ

Multiple elephant, multiple buffalo, giraffe. I published the all data and related photos of recovered bullets in African Hunter in 2005. Do you receive that magazine?

As an example, a .500 NE bullet with such a wide meplat that it is almost a full wadcutter penetrates about 50% deeper than a .375 H&H with a moderate meplat, even though the .375 H&H has a 400 fps velocity advantage.

Likewise, the .500 NE with flat nose solids generally outpenetrates the .470 capstick with flat nose solids even though the .470 has a 200 fps velocity advantage. And the .500 NE has a significantly larger meplat than the .470, when using FN bulles.

quote:

I think you have an affinity for large-breasted blondes my friend

And the problem is.......?

Peter.

quote:

Originally posted by jorge:
MR: Doanld Sutherland in the "Dirty Dozen" right? jorge

Exactly!

quote:

Originally posted by 500grains:

quote:

Originally posted by JJ_Miller:


What is your field experience with wide meplats..............JJ

Multiple elephant, multiple buffalo, giraffe. I published the all data and related photos of recovered bullets in African Hunter in 2005. Do you receive that magazine?

As an example, a .500 NE bullet with such a wide meplat that it is almost a full wadcutter penetrates about 50% deeper than a .375 H&H with a moderate meplat, even though the .375 H&H has a 400 fps velocity advantage.

Likewise, the .500 NE with flat nose solids generally outpenetrates the .470 capstick with flat nose solids even though the .470 has a 200 fps velocity advantage. And the .500 NE has a significantly larger meplat than the .470, when using FN bulles.

not to start the whole twist thing again..

but without a baseline you can not compare cross caliber AND shape without a function of converion.

comparing a 375 "moderate" (which means which? realative to bore or gross size?) meplate to a .510 with a large meplate (again, what is the MEASUREMENT) is like comparing LUP to PSI (never mind CUP to PSI)....

or
.375 apple

does not compare in a MEASURABLE SENSE to a
.510 orange.

and if you change the caliber, velocity and shape, you are now comparing apples to blue.


So, in order to KNOW what the comparison is, I feel the following should be done.

1: agree on a world-wide repeatable media
2: agree and abide by terms
3: agree and abide by conditions
4: define experiencements by the following
caliber
velocity
SD
Bullet construction matieral
SHAPE using bullet maker terms (X caliber meplate and shape)
5: run SINGLE variable experiements... for example, define direct comparison of a .375 .7caliber meplate, X SD, at Y velocity to directly compare to IDENTICAL standards, except with a .510 bullet.

6: define SINGLE variables thereafter..
after determining the same-same comparison, being changing ONE thing. Now compare a same same bullet, save caliber, with variations in velocity. to KNOW

7: build the JLS penetration index - JLSpi to actually KNOW the relationship from shape to speed to SD to MO to the cover of shorts one is wearing in the jesse.

BTW, I am still awaiting bauska to deliver the 1x10 twist .510 to perform said tests.


jeffe

Plywood tests do not accurately predict what a bullet will do in real game.

quote:

Originally posted by 500grains:
Plywood tests do not accurately predict what a bullet will do in real game.

Agreed

however, field guesses at multi variable pentration comparsion are not scientific.

However, plywood (MDF actually) WILL tell you how a bullets, shapes, velocity and just about everything else, react in MDF and can be tested and, most importantly REPEATED.

without being repeatable, it's just an observation.

quote:

Originally posted by 500grains:
Plywood tests do not accurately predict what a bullet will do in real game.

yep, honestly, I totally agree.

..accurately predict ....

500 grains,

I think what Jeffe means is that it is much easier to do the plywood pachyderm than to import enough elephants to do the test. I would hope that the ending shape and penetration of the various bullets tested would correlate to what you and others have found with recovered (from buff and ele) ones.

Rich
DRSS

The bottom line is that shooting plywood might be fun, but it does NOT tell you what a bullet will do in game. That has been proven repeatedly with all types of bullet testing media, with the exception of carefully controlled ballistic gelatin. But is is very hard to get the gelatine to be consistent batch to batch. And just look at the absurd results from the Linebaugh tests.

What really puzzles me is people who wish to ignore real results from the field in favor of an artificial test media that has nothing to do with big game hunting. Perhaps it is an economic thing.

It is already known that plywood does not accurately predict field performance of sloids bullets.

BTW, observations, called evidence, count not a little. Someday we will need to recognize the theory which explains the evidence instead of discounting the evidence because it contradicts a theory.

The evidence: 500gr .458" round nose solids compared to 450gr .458" flat nose solids indicates that the flat nose solids out penetrate the round nose solids by an almost 2 x 1 margin in elephant heads and bodies and cape buffalo.

JPK

quote:

The evidence: 500gr .458" round nose solids compared to 450gr .458" flat nose solids indicates that the flat nose solids out penetrate the round nose solids by an almost 2 x 1 margin in elephant heads and bodies and cape buffalo.

How come a .366/286gr steel-jacketed Wdl RN bullet shoots right through and elephant's head. Penetration is not the problem, rather missing the brain. People that used this bullet on elephant, like Ganyana, will confirm this.

Warrior

Warrior wrote

quote:

I thought that supercavitation was something that only happens in water and not in flesh, being a "soft" solid. Did Alf not explain this notion/phenomenon at length, or was he not convincing enough? Lutz's theory stand in contrast to Norbert's theory in this regard, I think. It would be nice if Lutz could also explain to us again what forces are at work or the mechanisms at work of a bullet inside an animal.

Hallo Warrior,

Definition 1: A soft Target is a Target in that the initial Stagnation pressure forces upon Impact by at least an Order of Magnitude outweigh the permanent Shear forces, needed to rip the Stuff into Pieces.

Definition 2: A hard Target is a Target in that the permanent Shear forces outweigh the initial Stagnation pressure forces upon Impact by at least an Order of Magnitude.

Hole: Between the two Definitions is a Hole for intermediate Stuff, often Composites, like Legs, Heads and so on.

After these Definitions, You find Meat, Gelatine, Wax, Soap, wet Clay and most important Water to fit in the Soft Target Category.

Bone definitely is a hard Target. Some Bone Structures You find in Head, like in Elephant and Buffalo contain so many Hollows filled with soft Stuff, that to categorize them is not easy. Most appropriate would be to handle them Layer by Layer.

When a Bullet above about 150 m/s hits a soft Target, the Interaction between the moving Bullet and the resting soft Target build Stagnation Pressure ½ * rho *v square, where rho means the soft Targets Density. At real Rifle Speeds this Pressure is great enough to yield or brake metallic Structures (the Bullet itself).

From the Discussion point of View, it makes no Difference, whether the Bullet moves and the soft Target rests, or the soft Target streams around a resting Bullet. I switch now the Picture and talk about the “Streamâ€, meaning the relative Movement of the soft Target to the Bullet.



Above Picture colures the relative Speed of the surrounding Medium around a moving Bullet. The Colours appear in Rainbow order, blue being slow and red being fast. CFD-Calculations output such Pictures, together with Numbers.

In the Mid front of the penetrating Bullet the Stagnation pressure is highest. How the soft Target streams around the Bullet, sometimes deforming, fragmenting, or completely destroying a Bullet, depends on its Shape and Material Strength, notably the Yield and the Shear strength. Relatively soft Bullets will yield to closely follow the Stagnation pressure Isobars on a flat Surface. Those are a flat Ellipsoid:



Stagnation Flow and Pressure Isobars from a 1920 Textbook from Prandtl


Prandtl, the Founder of Flow dynamics

Maybe You ever wondered, why most recovered Soft points have this typical Mushroom shape. Well, You see the Isobars. At or near the hard Penetrator the soft Target streams under enormous Forces, that in the Penetrators middle front brake the Speed, but off Center accelerate sideways. The Picture is a bit more complicated, as You might imagine, but the sideway Acceleration interest us most. As the stagnation pressure Forces on the dense Stream pushes sideways, the Flow leaves the Bullet. Only a certain Part in the Front is wet.

Duncan McPherson published some 10 Years or so a Book in which he analytically derived the Flow-cut-of-angle for a simple Shape, here a Ball. Less smart People with big Computers nowadays use CFD-Code to model such Flows. If the Shapes are not simple, this is the only possible Path towards a Solution. Such Code meanwhile is commercially available.

I postpone Warriors initial Question about “Superâ€cavitation and just state, or better repeat after Duncan McPherson: Above 150 m/s relative Speed hard Penetrators in soft Targets only wet in the Front.

You might now ask an what is around the Bullet then? Well in Meat or Water just Water vapour. If no Water exists then Vacuum. Water at Room temperature has only about 61% atmospheric Pressure. That’s on Reason, why temporary Cavities collaps so fast.

So every Bullet above 150 m/s in a soft Target is a Cavitator, if that shall mean they create a temporary Cavity around themselves in the Soft target. This temporary Cavity can be quite Large, especially when You shoot big and fast Bullets in not so big Animals. If the Cavity reaches about halve Animal diameter, the often simply explode. Varmint shooters know that well.

Penetration linear depends on sectional Density and somehow on Speed, less then linear. “Superâ€cavitation means a Trick in Bullet or Torpedo design, where it came from (rocket driven Russian Submarine Torpedos namely), where You carefully study the Flow around a Meplat, most important the Flows Cut-of-angle at the desired Speed in the desired Medium and make the Meplat a bit smaller, than the Penetrator Body. Thereby not the full Body diameter “sees†the Flow, but only the smaller Diameter Meplat, with less Area. Hence they penetrate “superâ€, compared to a full diameter sized Meplat ! When these now dubbed “Supercavitators†are carefully designed, the do as intended, an Penetration increases reverse to Area for an unpropelled Penetrator, a Bullet, not a Torpedo.

The Key Word in the last Sentence was, “carefully†designed. Care must be taken that the Flow actually cuts off, as intended, and wets only the Meplat. Even more Care must be taken not overdo the Concept and loose stability. But this is another Subject.

I will late return to the Subject of objective Measurement, to prove the Models. The Problem is not small. I know of an African Institution, that wants to test shoot all relevant Big Bore Cartridges with a Selection of the typical Bullet Designs to build dependable Database. About 20.000 Shot are envisioned to accomplish the Goal. Now when You talk the Numbers an a short Time frame, not a Life time, You cannot resort to Gelatine, Wax or alike. Her one must build an Instrument to track the Bullet in an easily accessible Medium, that must mo be cooked, cast and alike. I think the Time is ripe for such a Machine. I do not have it yet, but I want one. Then we uncover some Design faults or plain Lies rather easily. But until there quite some Water will pour over Victory falls.

LutzM

Warrior,

A side brain shot on an elephant is probably the shot requiring the least penetration. A frontal brain shot may require more or a whole lot more depending on the range and the way elephant is holding its head.

Maybe a fair penetrator will have enough, maybe not. Why settle for maybe when you can know for sure?

Take a broadside, quartering or going away shot and penetration becomes more critical, especially the quartering away and going away shots. Better to have a bullet that will get where it needs to go, right?

Four to six feet of penetration is better than two or three.

JPK

quote:

Originally posted by Jim Manion:
Definitely a perky design. Wonder what happens to it in the cold..

To digress, JudgeG is a man of great virtue. While there are many things that still surprise me in this world, a positive paternity test would not. Women take his kind ways as a sign of something different, forcing themselves upon him against his will. It is a curse few men know. For one victimized in such a manner, it takes a man of unique character to acknowledge paternity after being cruelly forced to surrender his seed. Yet, you will never, ever, hear him complain about these experiences. My hat is off to JudgeG.

Jim I wonder if you are still willing to digress with the Judge?

YIKES!

Well, er, hmmm. MAYBE he was assisting Lutz in coming up with his new bullet design?

quote:

Originally posted by Frank Martinez:

quote:

Originally posted by Jim Manion:
Definitely a perky design. Wonder what happens to it in the cold..

To digress, JudgeG is a man of great virtue. While there are many things that still surprise me in this world, a positive paternity test would not. Women take his kind ways as a sign of something different, forcing themselves upon him against his will. It is a curse few men know. For one victimized in such a manner, it takes a man of unique character to acknowledge paternity after being cruelly forced to surrender his seed. Yet, you will never, ever, hear him complain about these experiences. My hat is off to JudgeG.

Jim I wonder if you are still willing to digress with the Judge?

i had to wits away the laugh-spit on that one...(wipe wipe)

those do not look natural...has the judge, perhaps, had silicone implants?

Rich
DRSS

I am sure they were latex.
Frank



I am sorry to Hijack this but there is no category for his honour.

One reason the wide meplat bullets Dan has recovered from elephant are penetrating more is simply because they are heavier.

For this reason it is not very useful to compare a 550 grain .510 to a 500 grain .475 to a 450 grain 458, or a 300 grain .375.

Even if their SD is similar, like the the North Fork line (see photo below), the percentage of mass that contributes to the bullets energy has a significant effect on penetration. One of MacPhersons chapters has calculus to predict this.

Dan and Mike Brady at North Fork have conducted some interesting tests with 300 grain .375 using Truncated Cone FN vs wadcutter, both at identical velocity and copper alloy.

A Truncated Cone FN better supports the meplat than a wadcutter. (As Mike explained to me, "In engineering the triangle rules!")



You can make the meplat so wide it does expand.

I think Dan and Lutz are both correct. A smaller meplat will penetrate better in bone, while the larger FN (that does not expand) will do better in an elephant skull which has a surprising amount of blood in it!



Pictured above, my cow elephant skull cut in two behind the eyes. Pink square was FN that missed the brain (outlined in blue). Note larger than diameter hole in skull!

The La Grange stop box actually does predict penetration in elephant skulls very closely. . . for FMJ RN bullets!

It is a complete failure for FN.

And that is why Dan's body of work is so important.

After trying both the stop box and water for the last 4 or 5 years with FMJ RN, and monolithic RN and FN solids, I can tell you with some authority that the only appropriate test medium for an elephant skull is a dead elephant!

You can shoot 5 or 6 of THE SAME bullet into each elephant skull (3+ front-on and 2 sideways), and then compare for consistency and penetration with another bullet in another elephant.

You can repeat the test with body, hip or leg shots once you are finished with the head.

To test the effect of both fast and slow twist, and RN vs FN bullet, or moderate FN vs wide FN, you will need either 4 or 6 elephant.

With this many hunters on-board, using a common caliber, this should not be mission impossible.

The question is, how many people do you know who have actually spent the day and most of next day, mucking around in an elephant carcass at 100 degrees F? I know Dan has many times, and I have once. Have you?



PS Lutz, what copper alloy are you using?

Andy

Hallo Andy,

Great Pictures! Just befor Sleep a short Note on Copper. The Answer is: It depends on how I want to behave the Bullet. Plain electrolytic Copper it softest and yields most. On the other Hand it machines nasty. For Precision bullets, such as my KJG line, this is not good, so I use some Ingredients for better Machining to make it a bit more brittle. For a full blooded Deformator, not to rip apart, on would use Gild metal (Copper-Zink) and for a full Fragmenter Brass with a lot of Zink is best.


9,3 mm Bullets into Water and Sand, left Copper, right Brass


Brass bullets are brittle


Brass may fully crack upon impact


The cracked Brass Bullets became unstable, tumbled and hit the Sand on the Side, see the rough Surface.

More later. I hit the Sack now. Good Night

LutzM

quote:

Originally posted by Andy:

The La Grange stop box actually does predict penetration in elephant skulls very closely. . . for FMJ RN bullets!
Andy

quote:

Originally posted by 500grains:
Plywood tests do not accurately predict what a bullet will do in real game.

Andy, Dan, which is it?

Jeffe,

You are trying to stir up trouble where there is none.

You forgot the part about where I said, "The La Grange stop box is a complete failure for FN bullets."

Do not mis-quote me by omission!

This is a complex issue.

Here are the facts: 465 grain TCCI RN monolithic solid at 2,550 fps, 67.5 boards average (non standard 1-12 twist), equals 50 inches penetration.

Elephant penetration under 39 inches.

465 grain TCCI RN in water tanks, under or equal to 39 inches.

450 grain North Fork FN in water tanks, greater than 120 inches!

450 grain NF FN in wood stop box, 52.5 boards, or 39 inches wood.

450 gr NF-FN in elephant, greater than 60 inches penetration.

There fore my statement that only using dead elephant for a study of RN, FN and quick or slow twist is meaningful.

Unlike some here, I have an open mind. If an artificial test medium does not correlate to emperical results, I go back to the hunting fields.

So should you.

Andy