I bet you guys think you lost me

Ray,

I just added up the combined penetration of wood and air space and its 6 1/2 feet for the 450 gr NF FN, 7 1/4 feet for the full power .458 WM, 7 3/4 feet for the 450 gr RN or 375 H and H, and 8 3/4 feet for the 500 gr RN (at 2400 fps).

Does that sound reasonable to you or is it too much?

Andy

Penetration is a very complicated matter and test results are highly dependent on the methodology and the test medium used. The only value of artificial target media such as wood, wet paper, gelatine and others is to compare one bullet to another in that particular medium. Plywood and shooting into baffle boxes has little bearing on penetration in animals.

From the field and test experiments we observed two different mechanisms of penetration in animals:

1. The penetration in aqueous tissue; limited by the stability of the bullet�s travel in a supercavitation bubble; and

2. The penetration in bone, hide and sinews; limited by the forces acting on the bullet, (friction, shear resistance, viscosity).

Penetration in big game is often limited by the stability of the supercavitation bubble and unexpected bullet paths as reported often in big animals is due to this effect.

It is often supposed that if the base of a solid fishtailed, it hit something and flattened, causing it to bend into a banana shape and therefore deviated off course - missing the vitals.
That is incorrect. The process that occurs can be summarized as follows: First the cavitation bubble collapses and the bullet immediately becomes unstable. Due to this instability the bullet then tumbles. This tumbling exposes the bullet�s side or shank to deforming and/or deviating forces. Now it can be deformed and veer off course.
There is not too much to say about the high pressure in front of the bullet, but a FN or the SuperPenetrator causes much more wounding than conventional noses. The pressure cone we can see in shadowgraphs of a bullets flight in air is not existent in aqueous media, because the bullet is travelling with subsonic speed. We observe very low pressure in the cavitation bubble. Not the reduced drag in the cavitation bubble is the most important effect, but the stability against tumbling.

The reduced Ballistic Coefficient in air is minimal and has no practical effect for big game hunting.
A not too wide meplat as well as the SP bullet give up roughly 20% of penetration in plywood or bone compared with a Hornady FMJ, but "cannot stopped" in water cans. For animals hunted with bullets of a SD > 0.3 and a muzzle velocity near 2400 f/s this doesn�t matter.

The 500 gr Ho FMJ is not stopped in water cans, but becomes unstable and leaves the setup sideways. This was also reported by other authors. I used batteries of up to 20 water cans, 5 liters, each providing 18 cm of bullet path, in total 3.6 meters. This allows to follow the bullets path and its straight penetration with sufficent accuracy. Tumbling is indicated by the holes in the walls of the containers.

You cannot compare penetration in water with penetration in wooden baffles. Remember: We are confronted with two very different mechanics of penetration.

The nose shape of the SP and some FN will be retained in game, wereas other meplat bullets like the GS FN form its meplat by chance under impact and is somewhat sensitive to this.
A wide meplat itself doesn�t guarantee a better performance. You have also to look at the other design features. E.g. a meplat formed only by cutting a hemispherical RN shows no effect.

More on terminal ballistics:

Grosswildjagd

Norbert,

I just calculated the percentage difference between a base line 500 gr Hornady FMJ and these other bullets.

The 450 gr RN had 11% less penetration than the 500 gr. RN.

The 400 gr RN had 23% less penetration than the 500 gr RN.

The 450 gr North Fork FN had 16% less penetration than the Barnes RN.

The 450 gr. GS FN had 23% less penetration.

You have found a 20% difference between RN and FN, so it appears our results are very similar.

Some of the difference in penetration you have noticed may not be due to super cavitation but simply the difference in length, center of gravity, and center of form of your 450 grain Super Penetrator bullets. They will have more rotational velocity than the heavier Hornady, which made a difference of 3-4 boards (5-6%) in my tests.

If super cavitation is a factor in penetration, why did Duncan McPherson not see an increase in penetration with the SWC compared to the RN? His SWC profile had a very small meplat like the 200 grain H and G. Perhaps you can explain this to me?

I have standardized on the 450 grain bonded core North Fork at 2,550 fps for my 450 Dakota. My only interest in a solid is for cow elephant or hippo, as I will never be able to afford a bull elephant.

Would you agree that either the 450 grain Barnes RN or North Fork FN solid will be adequate for a cow elephant? I will use the North Fork soft point for everything else.

Thank you for your time.

Andy

Andy,
Sounds reasonable to me, and one has to remember flesh is tougher on bullets than plywood except in the penetration dept with solids.. Bullets seem to penetrate very well in plywood, its...but whatever medium one uses makes little difference as long as you use the same medium for all the bullets tested..Your only compairing one bullet to another...

The problem with testing solids is that todays solids made in the USA, have enough penetration to get the job done on any animal with a bit left over in most cases...I will include Woodleighs and GS Customs in that scenario...Others may well be as good, but I have had no experience with other foriegn bullets.

A solid is a well proven buffalo killer and they have been killing buffalo for a century or two with good results..Not to say that todays soft super premiums arn't excellent bullets most of the time...and the monolithics are painting a different picture altogether, but when push comes to shove I always want a few solids in my belt and a couple in my gun.

Andy,
you wrote:

>You have found a 20% difference between RN and FN, so it appears our results are very similar.<

The difference is between Hornady or Woodleigh FMJ RN (Kynoch profil) and the SuperPenetrator optimized for 2300 f/s with 7.4 mm disk. Our results are similar, numbers are depending on the actual size of the FN.

>If super cavitation is a factor in penetration, why did Duncan McPherson not see an increase in penetration with the SWC compared to the RN? His SWC profile had a very small meplat like the 200 grain H and G. Perhaps you can explain this to me?

I am not very familiar with the work of McPherson. Experiments on handgun projectiles (evtl. subsonic) are not comparable with high velocity rifle projectiles. A very small meplat requires a careful design of the whole bullet shape.

>Would you agree that either the 450 grain Barnes RN or North Fork FN solid will be adequate for a cow elephant? I will use the North Fork soft point for everything else.<

I agree that both bullets will down an ele cow but, if possible, I would prefer the FN. The Barnes is a true RN. It was not as easy as with the SP to down a cow with this bullet. I must give it three shots. It is said, that Barnes will change the design to FN.

In general, the tendency to use lighter bullets with modern copper monometals is a wrong way if maximum penetration is needed. To get a proper Penetration Index you cann�t compensate less mass by higher velocity in practical limits.
An example: A well placed frontal brain shot on an old ele bull with a .458 WinMag 400grs FN at 2300 f/s showed no effect! PI ~ 80 Don�t use for ele bulls! 500 grs at 2400 f/s PI ~ 131 Top class in penetration!

Gerard,

The 450 grain GSFN only went 2450 fps when I tested it in 2002 from a 460 GA. That is all the faster it would go. This rifle had a 1-10 twist.

I shot it at 2524 fps a few days ago from my 450 dakota, 1-12 twist.

It went perfectly straight in 2002 and veered off a bit this time after the 33rd board. It "only" went 47 boards, a difference of one board, two years apart with a slower twist. That is hardly inconsistant. I would be suspicious of data that was too predictable!

The bullet veered off I believe because the meplat expanded to .431 diameter, making it unstable. I'll e-mail you the photo.

I guess Ray and I are the only people here who expects a FN to have less penetration than a RN!!!!!

You cant have it both ways gentlemen. A FN does cause more tissue damage, and that is why we all want to use one!

Why would anyone expect a FN to penetrate more than a RN???

MacPherson did test non deforming steel spheres, wadcutters, SWC, and as I recall, a concial at up to 5,000 fps. (The concial may have been a private correspondance with me).

Norbert, if you dont have the book, Bullet Penetration, MacPherson, Duncam, Ballistic Pubilcaitons, El Segundo, CA, 1994, it is usually available from Amazon Books. It is out of print.

I did not expect my simple little test of solids to be controversial. I merely thought it was interesting.

Some of you have noticed that the test results coincide very closely to the so-called "Penetration Index," as outlined in The Perfect Shot.

My results were accurately predicted by Art Alphins formula for the 450 Dakota with 500 gr at 2400 fps, 450 gr at 2550 fps, 400 gr at 2676 fps, plus the 416 with 410 gr, and 375 with 300 gr.

The PI was about 10% off on the 375 improved, thinking it was actually better than it was, and about 13% off on the full power 458 Winchester vs 375, the 458 being better than the PI suggested.

Gerard, I dont have MacPhersons book in front of me now, as I leant it to a freind at Nosler. Can you look up his formula for predicting penetration? As I recall it took into account the percentage of energy a bullet had from momentum. I think it was in his chapter involving calculus.

I am curious if it would better predict the penetration results in boards for the 375 improved and 458 win mag.

Norbert, I looked at your web site and dont see any mention of you having used the 450 grain Barnes RN. Do I understand you correctly, that you used this bullet and the elephant required three head shots???

thank you all for your feedback.

Andy

Andy,

I know I am on the verge of running this topic into the ground of boredom, but one more.

I hate to bust your bubble of fear on braining an elephant. A side brain shot represents little resistance and can be accomplished with most anything. It is not going to require 3 of anything, Barnes RN, or otherwise, to down a elephant. The reason for using the big guns is for the times when things go wrong, when the shot is not quite so well-placed, or the penetration really sucks for no (apparent) explainable reason!

Thanks again for all your hard work.

Andy,

Did you have any of the Bridger solids to try in your test??


Mike

Some things come to mind:

Testing for hunting performance in wood is not the best idea as the results are misleading. Some publications have tested expanding bullets in dry paper packs and then wonder why bullets that fail in that medium, do better than the "tough" bullets from the drypack test, in the field. The two media, dry paper/wood and tissue are simply not comparable in their reaction to a projectile passing through.

Andy,
In your previous test, the 450gr GSFN penetrated 48 boards at 2450 fps. Now it penetrates 47 boards while going almost 80fps faster. On a brittle medium like wood, every test I have ever done resulted in more penetration when speed goes up. What has changed in your system that produces such a marked inconsistency? One of the advantages of a drive band bullet (GSFN and GSHV) is that it can be run at higher speeds than smooth sided or grooved bullets. Why not take advantage of this and run the GSFN 80 or so fps faster than the other 450gr bullets in your test? That is what is done under practical hunting conditions and will increase the available momentum and energy levels of the 450gr GSFN to 167.1 lb-f/s and 6756 ft-lb. (500gr Hornady = 171.4 and 6397)

I am concerned that you stated that the GSFN tipped and yawed to about 45degrees. Did it stil penetrate in a linear manner or did the bullet veer off the path? I design the FNs to be shoulder stabilised and, even if they produce oval holes towards the end of the wound channel, they tend to remain on course.

When doing water penetration testing, a lot of smaller containers work better than a couple of large ones. The last time I used two containers to stop an experimental 338 bullet, I put 90 liters of water into the air in an instant and completely destroyed the containers as well as the contraption holding them in place. That was only 300 gr going at 2600fps.

You are mistaken as far as MacPherson's testing is concerned. The tests he referred to that went to 5000fps were done with steel spheres and cylinders and were yield testing done by Fackler, Bellamy and Malinkowsky with no mind to penetration (p144 of "Bullet Penetration"). All testing done by MacPherson in gelatin for penetration with SWC, WC and RN bullets were done at handgun speeds. In chapter 8 he reports from p178 onwards on the penetration characteristics of various bullet nose configurations. The first observation is that round nose, conical and truncated conical bullets all had curved trajectories in gelatin that was consistent at 3" to 4" of curve for 20" of penetration. Cylinder shapes and Keith type semi-wadcutters produced straight penetration paths (p186).

MacPherson does little penetration depth testing of the various bullet nose shapes in his book. Instead he concentrates on the permanently disrupted volume of the cavity. Here he states several times that the maximum disruption comes with a cylinder shape closely followed by a sub caliber cylinder (Keith type semi-wadcutter). He comments that all other nose shapes are inferior to these and "differ little from each other."(p277)

The reason why MacPherson does not deal with supercavitation is because it does not occur at handgun speeds. He touches on cavitation in the section dealing with Newtonian flow and therein lies another clue to the superior penetration of cylinder shapes (from p97)

It is interesting to note that MacPherson states on p140 that "There is no detectable difference in performance between the flat nose and cup nose configurations."

Norbert,
I agree fully with all your comment except: ".....other meplat bullets like the GSFN form its meplat by chance under impact and is somewhat sensitive to this."

Our GSFN bullet meplats are machined to a very effective configuration for disruption in the wound channel and for supercavitation to aid penetration. Where extreme forces do produce a further flattening of the meplat, this simply serves to improve the shape and performance even further. See the pictures at http://gsgroup.co.za/faqdesign.html and you will see that there is no forming "by chance" of a GSFN bullet meplat.

On the subject of lighter monometallic bullets, one must strike a balance between weight and speed and the desired requirements are often contrary to one another. Speed aids supercavitation, but is useful only if it can be sustained. This requires momentum, which in turn is more reliant on weight than what energy is. There is a direct link between energy and wound channel volume, the more the better. Ultimately, the balance that can be struck is capped by the limitations imposed by the cartridge and the firearm. GS Custom Bullets exists to find the balance for each caliber and then to recommend what we have found.

Andy,
Your tests are very interesting.
The PI is a valuable measure for comparing penetration of bullets with similar shape. Not for number crunching, but rough numbers.

you quote:
>I guess Ray and I are the only people here who expects a FN to have less penetration than a RN!!!!!<
?? I always say the same. But it holds only for solid material. A virtuell better penetration of FN in animals, aqueous tissue and water tests is the result of its far better stability in tissue.

>Norbert, I looked at your web site and dont see any mention of you having used the 450 grain Barnes RN. Do I understand you correctly, that you used this bullet and the elephant required three head shots???<
My web site represents not all my hunting experience and is not a data base for bullet properties. More or less by chance I hunted three elephants with Barnes Solids RN, one required three head shots, the others also were not very convincing.

There is much conformation for the order of penetration (or stability) in animals: true RN, slightly changed RN to Kynoch profile, rounded FN, sharpe edged meplat, SuperPenetrator with its sharp and protruding disk.