Why do solids (nondeforming bullets) penetrate animal tissue and most artificial targets straight to a sufficient extent? In literature we find, following the results of Fackler e.a., the thesis, that all solids must tumble in aqueous media (tissue), and would not penetrate sufficient, because the gyroscopic stabilisation in air, caused by the twist, should have no effect in the thousandfold denser tissue. But they are going straight!

In a thread about a year ago, I discussed as an explanation the effect of supercavitation. The bullet is travelling in a surrounding bubble of water vapour generated at its nose. The trick is to surround an object with a renewable envelope of gas so that the liquid wets very little of the body's surface, thereby drastically reducing the viscous drag. The bullet is flying inside a self-generated gas cavity and overcomes the effect of water that produces 1000 times more drag resistance than air does.
In general, the idea is to minimize the amount of wetted surface on the body by enclosing it in a low-density gas bubble.

An open question was, which shape of the bullets nose is the best for maximum penetration. There is some discussion on a "cutting edge" to be better than a "pushing round nose" with respect to effective wounding and on a "shoulder stabilisation". But these theories are not generally well-founded.

Triggered by the disclosure of details of the "Kursk" torpedos, which reportedly also are using supercavitation and some reports from US labs, I made some experiments to improve the supercavitation properties of solids.
Experts believe that the nose of the "Kursk" torpedo features what is likely to be a flat disk with a circular shape. This is the all-important cavitator, which creates the gas cavity in which the object moves. I got some preliminary, but surprising results:

The test setup was a row of thin-walled water cans, up to 12, each 18 cm width, backed by a couple of resin bonded hard boards. 500 gr bullets were shot from a .458 Watts/Lott at 2350 f/s. Twist 1:14. Distance 100 yards. Reference was the 500 gr Woodleigh FMJ, the "Super Penetrator" (SP) as described below.

The observations:
--Shots through the water cans with the SP show a stable flight and a penetration twofold compared to the FMJ. The FMJ starts tumbling in the 5th can and mostly leaves the setup. The SP starts tumbling in the 10th can and sometimes penetrated can 11 and 12 and one hard board. The tumbling was a 90 degree turn, further penetrating broadside, no deformation of the bullet.
-- At 20 yards, stabilisation was not sufficient enough for a convincing interpretation. The angle of yaw has to be reached its minimum, the bullet being "asleep". But in any case, the SP was superior to the FMJ.
--On shots through the resin bonded hard board, which is melting on impact, SP bullets show a penetration 50 % more than the FMJs.
--Water and aqueous tissue is the most critical issue with respect to stabilisation. In the resin bonded board no tumbling or other kind of destabilisation was observed. In such materials and probably bone the forces acting in front of the center of gravity of the bullet are likely compensated by forces working behind the COG, the result is a straight travel through the target.

The "Super Penetrator", utilizing supercavitation, has two essential features:
--At the nose a hard, relatively small disk with a sharp, protruding edge (Abreisskante = tear off edge?), where the hydrodynamic flow is converted into an aerodynamic flow.
--From the nose to the cylindrical shank a conical or ogival shaped head with a not too big angle off axis. Ogival radius about 5 calibers. A cavitator in front of a semispherical round nose (radius 0.5 caliber) doesn�t work.

I learned that penetration is a very complicated matter and tests are very dependent on the setup and the materials used.

In practice the SP bullet should be useful only with cartridges with a low penetration index calculated with A. Alphins formula. Conventional bullets with a PI around 130 have plenty penetration ability.

------------------

Norbert - I think the quick and easy answer to your initial question is, what happens in the field is impossible to reproduce in lab settings. While buckets full of water or sand make cool bullet stops, they hardly represent live tissue and bone. One can theorize and test in the lab all day, but until several thousand live animals are shot and analyzed, little correlation can be drawn.

It has been proven in the field that solids with straight sides and either a round or flat nose provide the best penetration and track through an animal. Spire point solids were found to upset easily in an animal. If you are talking about an ele head shot or a frontal shot on a buff, there is a huge amount of field experience that clearly show what caliber and bullet to (and not to) use. Anything outside this box is experimentation.

I imagine that one could spend years attempting to develop a better solid, however, until it has spent years in the field, it would be difficult to convince many of us to use it. I am all for new technology, however, I hate being a pioneer. If you draw on history the pioneers were the guys always getting shot in the ass with arrows. Dangerous game hunting is exciting enough without worrying about bullet performance.

But for pure scientific discussion, hydrodynamic/aerodynamic flow is an intriguing concept. However, I find that most of us are placed in two categories - those of us who what to know how the grenade works, and those of us who simply want to pull the pin and what things die. I�m in the pulling the pin category....

Technology didn't get to the stage it is now by us being satisfied with it.
Otherwise we would be still stuck in the tress scratching our asses.

Ookoo says "What about if we could make a spear that could reach out to 100 paces on chalicothere"

Bookoo Says "what for? The pit trap is tried and proven and thus is all we ever need" And goes back to scratching his ass.

So where can we buy these solids Norbert?

Karl.

Norbert,
You will find that increasing "d" to 6 mm and turning a 2mm radius on the edge to bring 3/4 to 2mm, will improve penetration even more. This will reduce the nose angle off axis as well as reducing the overall length, further increasing the resistance to tumbling within the target. On our FN bullets we use a conical ogival shape and the penetration results are exactly as you describe for the SP. We dispensed with the use of a hard insert in the nose of the bullet as we could not prove any difference in penetration with the shape machined directly on the copper or as a two piece bullet. In some cases, when extreme stresses were imposed on the test bullets, the harder material insert led to a catastrophic failure of the bullet as a solid.

------------------
Gerard Schultz
GS Custom Bullets

Norbert:

I fear you may be comparing apples to oranges. It seems that if there is any merit to your caviation theory it would surface by changing the nose of the Woodleigh FMJ bullets.

By filing off the front of a FMJ and inserting the flat front, and then comparing penetration would be more legitimate.

I hope you are correct, but should compare the same sectional densities, ballistic coefficients, etc.

Will

Gerard,
d is 6 mm. It was an error in print. Compare D and d in the sketch.

Will,
read more carefully please.
Reference was Woodleigh FMJ, both bullets have the same sectional density, BC is not very meaningful in this aspect.

Filing off the front of a FMJ and inserting the flat front, and then comparing penetration shows no significant difference. I wrote:
A cavitator in front of a semispherical round nose (radius 0.5 caliber) doesn�t work.
The angle off axis is not small enough.

------------------

Will,
I can assure you that Norbert is correct about cavitation. It is not theory but fact. There are two ways to arrive at a bullet that takes advantage of cavitation: Manufacture it with the correct shape for a "cavitation nose" or design it so that a "cavitation nose" is formed upon impact. This can be done with a solid as well as with an expanding bullet. The important aspects of achieving cavitation is the flat cylindrical face presented to the direction of movement as well as the slight rimmed enlargement at the leading edge with a very small angle off axis or no angle at all.

------------------
Gerard Schultz
GS Custom Bullets

[This message has been edited by Gerard (edited 10-06-2001).]

Norbert,

I am recalling this from memory, but the aerodynamic "spike" used in the submarine launched ballistic missile fired by the Trident submarine increases the range of this very blunt RN missile by 1,500 km I think. Maybe more. The spike is a small diameter disc on the end of a telescoped probe that is errected once the missile clears the water.

This certainly proves the advantage of the missile following the less dense air behind the spike.

In Fackler and MacPhersons tests the Colt 255 gr RNFN penetrated less than a RN though.

Andy

Wow,

After earning a "master gunner" award as a Captain in the US Army's Field Artillery, I though I was somewhat of a ballistician. I guess not. Interesting thread.

Hoping to be able to load some of Gerard's 450 grain FNs (.458) in my 460 G&A before the year is out. Just waiting on the rifle for a bit more. Apparently the gunsmith was swamped with hunting season jobs so in my last discussion, I told him that I would gladly accept a delay in completion since I'm probably not going to "need" the rifle this year. The wait gets tough as time goes on, but I'm sure it will be worth it. My last mauser was a 2 year wait.

-redleg

P.S. I know I got off the topic here, but could one of you real ballisticians put some of the reasons for the nose-hard-disc bullet thing in layman's English for me?

Thanks!

I cann�t serve with laymans english.
Optimizing this bullet is very difficult and complex. Depending on the medium, it may be possible, that in very dense material a RN penetrates more than this FN. The advantage of the SP design is more pronounced, the more aqueous the medium is. And it depends on viscosity and other parameters, what is the optimum diameter for the cavitator in relation to the bullets diameter and angle off axis of the head.
A very inportant fact for maximum penetration in aqueous media (tissue) is also the twist of the barrel. In the water vapour bubble the stabilisation is not as easy as in air. So instead of the 1:14 twist normaly used in .458 calibers should be replaced by a 1:12 or even 1:10.
Especially important for close up shots: Bullets must be "asleep". Extremely not sufficent are some smaller calibers, e.g.some .223 military rounds are stabilized only at about 80 yards. At closer distances they tumble.

------------------

Norbert,

I believe you are correct that the bullet must have traveled far enough to go to "sleep". I've had close-in "finshing shots" with solids that performed poorly. My last was several weeks ago-a point blank shot at a down buffalo, Trophy Bonded solid at 2450fps fired upwards between the front legs of a down buffalo-failed to exit. I found the bullet in the spine fishtailed.

Norbert, have you found that the flatnosed solids actually penetrate better in the field? No doubt it is difficult to get reliable data from field shots because of their lack of reproducibility. You seem to have dedicated a lot of thought to solids and their performance. Which solids do you use and recommend? Thanks, John

Hope I didn't offend you by asking for a "layman's" description. That was more of me asking for the benefit of the board. I'm a degreed engineer, completing a detailed study of biology, and will probably enter medical school withing 2 years. But, I do find this an exceptional discussion - something I haven't given much thought to, and it has grabbed my attention.

Keep up posted.

redleg

Friends,

tomorrow I am off for the Zambezi valley to test the new SP bullet on elephant ond other game.
Hopefully I can post more in three weeks.

------------------

Norbert,
May the red god smile upon you. Good luck to the intrepid soul. Kill 'em and autopsy 'em and recover those bullets. Very interesting thread. Glad to hear the barrel twist recommendation. I think you are right on.

redleg155,
Did you see the G&A 500th Edition magazine? (Nov.? 2001) It has the original article on the 460 G&A featured, from 1971 or thereabouts. They must still think it is the ultimate dangerous game cartridge. Can't say I would disagree. Brain child of Tom Siatos. Beat Saeed and Roy by about 30 years. A rose by a different name would smell as sweet, nevertheless.

------------------
Good huntin', shootin', and spear chuckin',
RAB

P.S. redleg155: It is not too late to reconsider medical school. But,hey, somebody has got to do it.

[This message has been edited by R. A. Berry (edited 10-15-2001).]

Norbert,

I wonder how you strike a balance between penetration and shock transfer/tissue damage to the game.

Personally, I am impressed with the theory of GS custom FN solids because that large flat meplat will make a big SPLAT! when it hits a big water bag (mammal). I plan to try a .470 caliber on a buffalo next month. But I am puzzled that the same structure also seems to maximize penetration.

In contrast, traditional round nose bullets like woodleigh seem to cause less tissue disruption and achieve less shock transfer, so I would hypothesize that they would penetrate further. But that does not necessarily seem to be the case.

By the way, I am planning on a broadside shot at an elephant with a 585 nyati shooting a 750 grain TCCI solid bronze RN solid at 2250 fps. Do you think the bullet will exit (a)if it does not hit a shoulder, (b) if it does hit a shoulder? Also, do you think that load is adequate for a frontal brain shot?

Thanks.

Dr. Barry,

Thanks. I'll have to get a copy of that magazine too.

redleg

Andy,
Can you recommend any reference material for light armour piercing rounds in small arms and the theory behind etc. Assuming it isn't sensitive material etc.

Karl.

I would like to throw a question into the ring. The shape, profile, design that LBT used for the rifle cast bullets, sounds like it would be just about ideal if reproduced in a FMJ. A large meplat, just a bit smaller then the diameter of the bullet. Am I mistaken in this thought?
A second question, if you will. Would there be any advantage to using a outside jacket of heavy gilding metal with mild steel jacket inside of that, with the lead alloy core?
Jim

Karl, Redleg and freinds,

Re. the 460 GA, I recently tested Gerards 450 gr FN in my 458 x 404 (same as 460 GA but with 25 degree shoulder). 93 gr Bofors powder similar to RL-15 gave 2450 fps in my short 21 1/2 barrel. Probbaly go two more grains for 2,500 fps. For comparison, the 450 Kodiak (one of best bullets tested for frontal area and retwined weight) used just 88 gr same powder. So his moly coat and engraved driving bands do make a big difference.

Have not killed anything with this but it will split a five gallon bucket in two which no other FMJ will do. It had about 20% less penetration in my wood stop box than a 500 gr FMJ RN at 2400 fps but tore the hell out of the box!

Steel jacket with flash coating of copper with wither lead or mild steel (B50 on Rockwell) are very common in Soviet/ East block bullets.

Small arms to anti-tank guns penetrate pretty much with energy divided by unit of frontal area. this works for fragments as small as 0.1 gram to 2.5 Kg 120mm APDS-FS at 1650 m/s.

There is a (classified) emperical form factor for the hardness of the core material. But if you are assuming standard construction between bullets you dont need it.

MacPherson has emperically proven formula for penetration in tissue which has factored percentage of energy from momentum (vs velocity).

Andy

[This message has been edited by Andy (edited 10-15-2001).]

follow-up:

1. Wouldn't penetration be increased if the bullet had a durable low-friction material on its exterior, such as teflon or whatever? Since moly seems to come off rather easily, I am assuming that penetration is not assisted by a moly coat. Has anyone done any work relating to improving penetration of hunting bullets by selecting the appropriate exterior coating?

2. I have a theory why the GS bullets penetrate so well in spite of their large flat meplat which intuitively should lessen penetration. The sharp ridge at the shoulder of the bullet should act as a cutting edge so that flesh of the game is CUT rather than STRETCHED as it would be with a traditional round nose bullet. Cut flesh won't hold a bullet back, but stretching flesh will. Just a theory.

500 Grs.
As one of the first pushers for a flat nose solid, I found out years ago that by turning the noses flat on Barnes, and all the other monolithics that they penitrated more than enough or through and through most every Buffalo shot with them and they did considerably more internal damage and left much better blood trails due the the rings or shoulders, which ever the case may be, a wadcutter effect if you will...I get the impression that the Flat nose drives strighter and has no tendency to turn as the RN may do on rare ocassions...velocity has a lot to do with this I feel sure, as you can drive a solid too fast in RN configuration and things will go to hell in a handbasket....

My early experiments were limited to a modified FN solid up as they would not feed for beans, followed by RN.... GS solved all this, they feed like poop through a goose...

The bottom line is simplicity itself, The flat nose GS kills better and has more than enough penitration from any angle...It may or may not penitrate as much as a RN, don't know, you'd have to ask the trees and dirt on the other side of the Buffalo...

Will that 750 gr. completely penitrate an elephant if no bone is hit...It will barely do so on ocassions, but not always, the off hide is thick and very absorbing of bullets. but I assure you that you are well armed for the job....and you can expect to see the elephant near cave in on the shot, the big 5's are very impressive to the eye, as compared to the lesser calibers.....

------------------
Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

Back from a field test, I will give some answers in order of the replying posts:
ZeroDrift:
The first objective of my experiments was to come up with a sound explanation, based on rules of physics, why solids do not immediately tumble in tissue, as experts in ballistics say they must tumble. They always argue with the 1000fold denser material and the then acting forces.
There is no idea to convince people to use SP bullets, because all solids are generating supercavitation to a more or less grade.
JohnDL and R.A.B.:
Your observation on close-in finishing shots is often made and was in the past pretended to poor bullet construction, but it is the angle of yaw.
I tested the new SP bullet a week ago on two elephants frontal head shots. Penetration and stability was extreme good. But a valid comparison was not possible, because also my 500 gr Woodleigh at 2350 f/s was penetrating as well and all bullets from frontal brain shots were disappearing in the guts. In the stress of a hunt, which had also other objectives, it was not possible to recover the bullets.
So, if you have the right cartridge with a penetration index around 120 to 130, you can use any modern solid.
But with my very preliminary results, I made an observation: The entrance hole of the bullets (only a few inches apart on the same ele head at the same time) is much smaller for the SP bullet than for the conventional FMJ.
500grains:
The balance between penetration and shock transfer or energy dissipation on the travel through the animal has to be worked out. The entrance hole indicates, that there is a lesser splash as it is with the conventional bullet design. The actual SP layout is good for ranking shots or shots from stem to stern. For normal broadside shots the trade off should go to less penetration and more energy transfer at shorter paths by increasing the diameter of the cavitator (the flat steel disk).
An exterior coating of the bullet will only decrease the friction against solid material. In the case of supercavitation it has no effect.
There is no indication of an influence of cutting or stretching. Our daily experience with cutting and stretching something is so different from what happens on a bullets impact.
A .585 750 gr at 2250 f/s PI=98 a) may exit, if the angle is right and no ribs, b) probably no exit hitting a shoulder. A frontal head shot is ok, a second finishing shot should be given, when the ele is knocked down.
arkypete:
The disk or evtl. a meplat generates the supercavitation bubble, its diameter determines the energy transfer and amount of penetration.
Using the SP principle with jacketed lead core bullets results in a shorter bullet with the same features and is advantageous for some magazine cartridges.

------------------

/

I recently shot a deer with my 416 and theGS FN solid, (out of curiosty,) the deer hit behind the shoulder dropped at the shot...

I will be using this bullet on some hogs this year and of course Buffalo very soon...It seems to kill like a soft point..and meat waste is a little more than most solids...and perhaps a little less than most soft points..about like a 220 gr. 30-06 If I were to compare. A very interresting bullet indeed.

------------------
Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com