You guys who are technically inclined will find this enlightening. It is from the February issue of SA Hunter magazine See Here

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Originally posted by Gerard:
You guys who are technically inclined will find this enlightening. It is from the February issue of SA Hunter magazine http://gsgroup.co.za/CB.html

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Heh,heh. Bekker would make more sense if he would just stick with the BSI (Bwana Saeed Index) and BAM (Bullet Area Momentum) values that I have pioneered here at ar.com.

I still say his Bekker KO values are a knock off of the BSI, and much less useful.

Of course the ultimate is the RIP value (Recoil Indexed Product).

Bekker has too much time on his hands. At least I have moved on to other things.

Truly, I have found his articles mostly rubbish except one nice piece on the Mauser 98.

I am at work and posting between patients.
I will give you a real review later.

I can't believe I actually raid that all the way thru!!
I think there's at least a dozen folks on this forum that could say all that in one sentence.

How about this.....use the bullet that is designed for the velocity you're driving it at!!!

Either he is shooting square bullets, or his cross sectional area calcs are wrong. Doesn't affect his final numbers, as the error gets lost when he 'indexes' them but I just sayin' I find it pretty unbelievable how well the penetration index mathes the momentum-area index.

The article is a response to one I wrote for the Big Bore Journal wherein I made the point that SD is not a good indicator of the penetration ability of a bullet. My opinion is that bullet construction, energy and mainly momentum are the real indicators.

Chris believes that SD is most important and sets out to prove this in his article.

Taking the test results from his article and checking everything for calculation errors first, it is interesting to note that his "indexed" penetration calculation is:

Bullet/Penetration/Index
175----63cm--------100
142----53cm---------84
108----42.50cm------67

The "indexed" SD table he gives is:

Bullet/SD/Index
175--.310--100
142--.252--81
108--.191--62

He goes through a lot of massaging and convolution to try and link SD to the penetration numbers. As he is so fond of "indexing", all he had to do was take the momentum numbers and "index" them to arrive at:

Bullet/Momentum/Index
175-----59.75----100
142-----50.51-----85
108 ----40.27-----67

There you are, his own experiment proves beyond doubt that momentum is a far better indicator of penetration than SD.

Thanks for getting to the point there Gerard.
Point well taken.
BS, BAM, and RIP are just for fun.
Bekker is serious. He should be pitied.

I quit reading at the point where he said he didn't run any monolithics faster than 2700 fps.

That tripped the "why bother" alarm. If you don't run them over 2700 fps, why bother using monolithics? JMO, Dutch.

Dutch,

The test he did, by reducing the length of the bullet while keeping the front unchanged, is very good. We have done this many times when developing a new bullet. Where his test falls down badly is when he "massages" the test to suit the outcome he requires.

Remember that the purpose of the test is to prove that light bullets penetrate less than heavy bullets. So to enhance this effect with the lighter bullets, he also runs them at abnormally slow speeds. The factory spec, which is low to start with, runs a 140gr bullet at 2700 fps as opposed to his 2490 fps. There are no factory loads for a 110gr bullet but I have used 120gr Sierra bullets at 3100 fps, so a 110 should be used at at least that speed, instead of his ridiculous 2610 fps. Hodgdon has specs on 100gr bullets at 3300fps that are within pressure limits.

The fact that he does not want to exceed 2700 fps for fear of breaking off the petals, proves that he has no grasp on the concept of how monometal expanding bullets work, or it is merely an excuse to justify his "massaging".

Gerard
What's wrong with the big heavy, flat nosed moderate velocity bullet? The bullet starts out at 40-45 caliber, may or may not expand, but punches a full diameter hole all the way through, at the very least.
Jim

Hi Jim,
Nothing wrong with large flat fronted hard cast bullets for handguns and low velocity lever guns. One would be hard pressed to improve on a Keith type bullet in these applications. In fact, our FN dangerous game bullet is an unashamed copy of such designs in the profile of the nose section of the bullet. There are some examples here.

The issue on this thread has to do with smaller calibres and I am sure you would agree that anything over 2500fps, intended for game out 300 paces, would be better served by some form of expanding bullet, not made only from cast or extruded lead.

Gerard
I was chatting with a professional hunter from South Africa a couple of weeks ago. Of course, the conversation turned to calibers and rifles.
For plains game, the four footed 1,000 or under critters, he allowed that a 25-06 with a 120 grain, well constructed bullet, would be acceptable.
The Sierra 120s are very accurate however I'm unsure as to the construction of the bullet itself.
What's your thoughts on this?
Jim

Jim,
Solid copper expanding bullets are currently manufactured by ourselves (SA), Barnes and Groove Bullets (USA), KJG (Germany), Sauvestre (France) and two companies in Scandinavia (the names escape me). There are probably more but these come to mind immediately.

Manufacturers of solid shank bullets with bonded core lead front sections are Northfork USA, Reichenberger Germany and Rhino SA. Failsafe has a copper front and a lead cored shank with a steel cap at the base.

These are all good bullets and the only ones I would use on a hunt where the stakes are high. High stakes in my book is not only when I stand to lose a trophy fee if the wounded animal escapes or turns on me with revenge in mind, it includes killing any animal, regardless of size or purpose, with one exception.

Bullets that disintegrate on impact is the very reason why we got into the bullet making business in 1992/3. In the 20 years preceding that, I just saw too many incidents where animals were recovered hours, days and weeks later with horrible wounds from bullets that failed. The vast majority of these hits were called as missed shots and the shooters went their merry way back home.

If the bullet is constructed mostly of lead with a copper skin over it, impact speeds over 2200fps add a risk factor that I am unwilling to accept.

The one exception I mentioned, is where the animal is so small and the energy and momentum carried by even the worst bullet on the planet, is sufficient to cause mortal trauma.

Gerard
Thank you very much.
I should be down you way some time in May for a ten day hunt.
Jim

SD is an important factor, but only with conventional bullets for the most part..

the world of the monolithic has changed the whole picture from what is the accepted norm, but we still have folks trying to apply those old figures to these new bullets that will shoot through two Sherman tanks, 4 Iraq pontiacs, skip across the Karoo and take out two tembos, 3 sudanees govt. officals and along the shoreline to bust up a jelly fish and come to rest in the Korean Ambassodors bathroom...at least I had that happen with a GS Customs flat nose solid one time

SD, don't leave home without it.

.

I do not think SD is any kind of indication of bullet performance. In every example one could possibly come up with, SD is always coupled to some other parameter that is actually the real indicator. SD on it's own tells us nothing.

Lets start with two bullets sitting on their bases on a loading bench top. One has an SD of 0.33 and the other has an SD of 0.15.

Despite a difference of more than double the SD, they are both doing exactly the same job of penetrating the surface of the bench. SD tells us nothing.

(Anyone who gets serious to the point of having a stroke about this will not receive the courtesy of a reply.)

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quote:

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My opinion is that bullet construction, energy, and mainly momentum are the real indicators.

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Gentlemen, no need to get too excited here. Gerard is quite correct with regard to the physics; it is momentum that keeps a bullet plowing on. It all goes back to Sir Newton's observations a few centuries back.

The fellows in the SD camp are on the right track, though. Keep in mind, that increasing SD with a given cartridge decreases V (muzzle velocity) less than M (bullet mass) goes up; and soooo... increasing SD increases momentum (M*V). If the bullet expansion is the same, increasing SD tends to increase penetration. That's what experienced hunters have been reporting for about a century now.

What has me curious, though, is what is the optimum speed for these newer, mono-metal expanding bullets. The consensus seems to be that driving cup-and-core bullets outside the range of 2100-2400 fps is not for the best. Too fast and you risk a break up; too slow and you loose whatever benefits velocity brings to wounding.

These new bullets, though, aren't nearly as likely to break up, so should one go for speed? I gather that if driven too fast, the petals shed and one still gets penetration, a nice balance. But is the damage from these speeds worth the risk of penetrating with a bullet sans petals? Or should one go for a more modest speed, say 2400-2700 to insure a bigger diameter (ie. petals still on)? One book on my shelf (by a Gregor Woods in Africa) suggests 2400 is still an excellent speed, even for the new generation of bullets.

What say those in the know here?

Karl

ASDF, you are kind of thinking about it backwards.

When using monometal bullets, you CAN run them up to extremely high velocities (I have shot elk with 7mag bullet still travelling at 3300fps), without giving up terminal performance.

What monometal bullets give you is the advantage of increased speed, coupled with high B.C. bullets, without giving up the ability to do work. That reduces wind drift and flattens trajectories, with terminal performance equal to, or better than, traditional heavy-for-caliber projectiles. JMO, Dutch.

I've been saying that for many years. In fact about three years ago I wrote a letter to RIFLE SHOOTER magazine in response to an article by Col. Craig Boddington, where he states the old (but wrong) axiom that "SD means penetration".

I was surprised because the printed my letter!

Anyway, you can use many demonstrations to prove this, but the important thing is that we put an end to this biased notion.

To Gerard: You once asked what I was using a .228"
bullet in...don't know if you got my reply...its a
.22 Newton. And I'm still searching for any bullet maker who will make .228" jacketed bullets in a
90 gr. weight. Any ideas?
Thanks, Tom

bisonland,

You could buy some Corbin bullet making equipment and make your own .228" bullets.

Alf,
The heavier bullet will penetrate better. We assume that there is no deformation of either bullet. The reason for the higher level of penetration of the heavier bullet is because it has more momentum. Let us say that one bullet was made from aluminium and the other from copper. Ascribing the extra penetration to SD is as logical as ascribing it to the fact that it is copper coloured and not white like the aluminium bullet. Here is the proof:

Using the same two bullets in your example, we slow the aluminium bullet down and we speed up the copper bullet. Now the copper coloured bullet penetrates even better and the white bullet penetrates even less. The colour or SD of the respective bullets did not change but the level of penetration did. Why?

asdf,

" If the bullet expansion is the same, increasing SD tends to increase penetration."

The reason why your statement above seems true, is again not because of increased SD, it is the fact that increasing SD results in less mv and therefore higher bullet integrity on impact. So bullet integrity is the penetration driver and SD is along for the free ride. The proof is: Fire two bullets of the same caliber and weight (equal SD) into the same medium at 3000 fps. One is a jacketed hollow point match bullet and the other is a solid copper flat nosed bullet. One will go way deeper than the other, despite the fact that the SD of the two was identical.

The interesting thing is that SD has a link to terminal ballistics. Two bullets of differing weight but equal construction type and caliber and at equal speed, impacting on the same medium will result in the heavier bullet expanding more. Increasing SD therefore causes more expansion if all else is the same.

On the subject of optimum speed for monometal bullets Dutch has a handle on it. I am not sure that we have found the answer here. I currently hunt with a wildcat .224 and use a 40gr bullet at 4700fps. Plainsgame up to 200lbs fall over like clockwork and, of the 40 or so animals I have taken with the 22, one blesbuck that was lung shot went about 50 paces. There is some information on this machine on the Articles page on our website. I have seen Eland taken cleanly, breaking one or both shoulders with 130 and 120gr HVs. Calibres were 7x57 and 7.21 Lazzeroni at 2900fps and 4000fps. Both 7mm bullets were recovered. So the jury remains out on optimum speed for monos.

Gustavo,
I agree completely. SD should go the way of "hydrostatic shock". It has been disproved too many times.

Bisonland,
We could easily bump up our 60gr 22 Savage bullet to .228" but I cannot help you with jacketed bullets. Sorry.

500 grains: Thanks for reply...I've already contacted Corbins...I very well may have to roll my own all right! I'm trying to find out what my start up cost would be...waiting for their reply,
I may be able to use my own reloading press...
they're the pros so will be highly interested in
what they will say..
Tom

Thanks for reply, I can very well use the Hornady
70 gr, .227" bullets...
but my intention is to use what Newton used & the
early experimenters...Gebby, Ackley, Donaldson, etc
& use a heavy 90 gr. .228" bullet, not as varmint or target bullet, but a long range Game bullet.
Tom

Gerard, no quibbles from me here; I did preface my assertion with "if the bullet expansion is the same." I quite agree with your comments on SD's effect upon penetration and expansion.

I must admit I'm still leery of the claims of the hyper velocity camp, but perhaps it's because all of my rifles are chambered for medium pressure, low speed rounds.

So, Gerard, if you were limited to speeds of around 2200 fps, what would you use for bullets? Conventional or fancier?

Velocity is a dynamic situation, a 270 win 140 grain BC .497 leaves the muzzle at 3170 fps, is going 2600 fps at 300 yds, and at 500 yds. is only going 2200 fps. So what is needed is a bullet that will perform at all these velocities.

Tough job.

Dynamic it is. I was referring to a muzzle vel. of 2200, which is about all one will get out of a rolling block with any significant SD.

.

asdf,
If it were impossible to launch a bullet from a rifle at more than 2200fps, monometal hunting bullets would never have come about. There are any number of bullets that will perform perfectly at those stress levels. My choice would be Nosler Partition or Swift A Frame.

woods,
A properly designed mono will do what you ask and more. How about a perfectly formed classic daisy petal expansion at 1900fps and better than 80% retention at 4000fps from the same bullet?

Alf,
"If I take two solid monometal projectiles of equal caliber, profile, equal length but one of greater "mass" than the other and launch them at equal velocity the one with the greater SD will outpenetrate the one with lesser SD."

OK, let's use this example. Let us say that when you fire the bullets, they are both going at 2200fps. The low SD bullet gives 10cm penetration and the high SD bullet gives 15cm penetration in your medium. Now I come along and borrow your test medium, to exclude variables, but because I am a speed freak I run both bullets at 2500fps. Same SD, same speed, same medium but both bullets now penetrate deeper. The colour has remained the same, the SD has not changed but the momentum of both has increased. So my statement stands. Change the momentum and the penetration changes. Change the SD and the resulting momentum change will lead to a change in penetration. It is much easier to skip right through SD and deal with momentum from the outset. The result is more credible and the test that Chris Bekker did, that I referred to at the beginning, proves this beyond doubt.

.

Thanks Gerard. I had seen some expansion & penetration tests suggesting some of the new breed of mono-metal bullets expand as reliably as (or even better than) many conventional bullets at the lower impact speeds (1800 to 1900). Forming petals instead of mushrooms allowed better penetration, though, and that is what has tempted me to try them in cartridges for which they were not designed.

.

I'm really not tryng to be a smart ass with this question, but I wonder why Chris Bekker can't post on these forums himself? Several times now I have seen other forum members post replies for him. What's the deal?

-Bob F.

BFaucett,

He has had some problems logging on and has not been able to do this even with a new account for some reason. I just received a couple of mails from him and shall post them after this reply.

Posting for Chris Bekker:

Gerard,

You say SD deserves a 'free ride' and is not indicative and I should only have looked at momentum instead of all the other factors that I used. Thanks for trying to simplify it for me. I stated that penetration mechanics are far more complex than the simple formula's or indexes, right? I specifically mentioned that scientists constructed complex penetration models - you must have conveniently missed that. We also know that these same scientists differ with each other as to which technique is better, etc and what should come into the formula or not. Both Dr. Norbert Hansen and Lutz Moller sees value in SD, but they have 'scientific' differences with each other. The reality is that if we engage 10 scientist, we will get 10 different models.

Let me now draw a simple analogy for you, since you want to simplify things for me. Let us shoot a 180-gr mono-metal ball and mono-metal bullet at the same velocity into say a wetpack. This will yield the same momentum. Which bullet will penetrate the deepest? I bet you it will be the bullet? Why? When you put more weight behind a given diameter (SD concept) it is bound to penetrate deeper despite the same force (momentum) that we have applied. So momentum is not the be-all and end-all, even though it is a driver. The Cross sectional area (XSA) of the ball is bigger than the bullet and now creeps into the equation. So XSA become a driver, right? XSA is related to SD, not so? Just as momentum cannot be used in an absolute sense, SD cannot be used an absolute sense as it is a static ratio of a bullet that does not describe motion. That's why momentum/XSA attempt to bring in both parameters by describing the force applied over the area. As it turned out, this formula correlated amazingly well, it was not a pre-conceived recipe to trick you with.

Don't accuse me of massaging my figures, they are actual results. Now you blame the result because the velocity is too low for your liking. You want to engage another variable of letting the petals fly off at high velocity and so engage a smaller XSA so it can penetrate deeper. That is what you want to see, but hold your breath, I am about to do that test for you when I have a chance. Penetration dynamics are not simple. Adequate penetration is important but not the be-all and end-all. There are also other important terminal factors, but we are not discussing that now. Don't believe for one minute that I am ignoring bullet construction, but I am sure you will appreciate the near impossibility of putting numbers to that. In my next article for SA Hunters I will deal with the importance of bullet construction, alongside SD, as an equally important matter of bullet performance. Not exclusively with penetration in mind, but with terminal effectiveness on game.

I tried to evaluate SD on a pure basis without the effect of other variables. Your purpose is to cut across all variables and prove your bullet is the best in the world under all circumstances. That is fine with me as your bullet has many fine features (innovative design concepts) and has definite niche in the market. What I do not understand so well is that on the one hand GS Custom claim that Lutz Moller stole your idea and when I refer to his bullet as a close copy of your bullet, you deny the similarity and say I am too dumb to see the difference. Close copy does not mean exactly the same - it is similar. In other words it is not so dissimilar that that his bullet looks like a frog. You see Gerard, this kind of argumentative double talk is part of your nature. You also tried to twist the facts by saying that I am trying to hint that I am now also a scientist. Read it in context, but no this is your way of getting the knife in ... but this is the nature of the beast. You also say I am sniping at you, I mealy took you up on your invitation to respond to your article on your site where you invited anybody that has the balls to differ with you. You tried to ridicule the concept of SD ... I attempted to prove that it has some value, not absolute value as you cleverly try to twist my words and put me in an extreme box. You labeled my article as another amazing article to create the illusion of non-relevance, but what is truly amazing here is that you are continually trying to put things out of context, cast doubt and then get personal.

Regards
Chris

Dear Chris,
Where to start? At the top I suppose.

My statement was that SD is always along for a free ride which is the exact opposite in meaning to "deserving a free ride" and nowhere did I say that you should only have looked at momentum, I said that momentum is a better indicator of the likely performance of a bullet than SD and your test with the Barnes X bullets proves it beautifully.

The rest of your tome above consists of a further 5 similar statements miscontruing what I said, 3 assumptions of what I am thinking (crystal ball working overtime), 2 irrelevant examples and several personal attacks on me when all I did was point out where you are making mistakes or make no sense (like your statement that that our HV bullets are smooth bullets).

Chris, it seems to me that your style is to launch character attacks on those who point out where your "science" is lacking. I did however state that I will henceforth be relentless in pointing out your technical errors when you involve my products, so here goes.

You give a very clear and typical example above of how your logic circuits work.

1. You state a position (180gr ball and bullet into wetpack)
2. You state the obvious outcome (bullet goes deepest)
3. You state your desired outcome ((SD concept) it is bound to penetrate deeper)
4. You engage in fuzzy logic to make the connection (XSA is related to SD, not so?)
5. Then you "prove" your point with the wrong assumption that SD has somehow become a force (That's why momentum/XSA attempt to bring in both parameters by describing the force applied over the area.)
6. And finally you get lost completely by referring to a formula that has nothing to do with the point you are trying to prove about SD (As it turned out, this formula correlated amazingly well)

The bottom line is that, on the subject of SD the foremost authorities do not differ. Note that I would not count myself amongst them in a month of Sundays, my technical training is too woefully inadequate.

The definitive work on bullet penetration and wound trauma by Duncan MacPherson consists of 301 pages. On pages 142 and 143 he devotes slightly more than half a page to SD. He correctly ties SD to the degree of bullet deformation that occurs on impact and says, under the title, Effect of Sectional Density:

"An increase in (undeformed) bullet sectional density will cause equivalent expansion at lower velocity."

If SD were as important as you make it out to be for penetration, why only half a page out of 301 and no mention or linking of SD to ability to penetrate?

HTL, who has vastly more expertise on the subject than the two of us combined, states in his paper:

"The following parametric study of the effect of sectional density on bullet performance should largely lay to rest the oft-quoted generalization that heavy for caliber bullets or bullets of some particular sectional density penetrate deeper and retain more mass."

Regrettably I have come to distrust your technical abilities because of the large number of errors you make. Be honest, would you take a technical article seriously if it is written by someone who cannot figure out how to get onto this forum?

Why do you have to say everything twice?

Kind regards

Gerard

PS. I am not alone in my opinion of your technical writing. Here are some comments from experienced people from this forum alone:

"Okay, my opinion: A little bit of knowledge is a dangerous thing. Apples aren't like oranges. The author is using fuzzy logic and worse."

"The author's analysis rings false to me."

"Reader Beware: Chris Bekker is a poseur and not competent to address technical matters in ballistics."

"Not to mince words this article is complete Bullshit. The author uses completely ridiculous logic unfounded by any scientific principles."

"It seems like every few weeks some new troglodite has an epiphany that envisions rotational forces having a profound effect on terminal ballistics"

"Things unraveled fast when we multiplied foreward momentum by rotational force.....WTF is that?"

"The most frequent real reason for such stuff is that the writer does not understand the existing science."

"Truly, I have found his articles mostly rubbish except one nice piece on the Mauser 98."

"I can't believe I actually read that all the way thru!!"

"I quit reading at the point where he said he didn't run any monolithics faster than 2700 fps."

Guys, what am I missing here? When I go buff or ele hunting, I will have handloads for my 375H&H, my 416 Rigby, and my 500/416 Kreighoff. My solids will all be GS Custom FN's which are very accurate and penetrate like hell. Whether it is the SD or the momentum, I really don't care, and besides, they look good! I can't comment on the HV's as I haven't really tested them yet.
Peter.
Peter.