quote:

Originally posted by BigFiveJack:
Well, I know a man with a 600 NE and 24" bbls. At 900 grns bullet

weight I think the Sec Den is .334 - WOW! He's chrono'ed it at 1700

fps with the historic loads. Many elephant heads have been pierced

with such a load. The SD of a 600 grn .458 bullet is well higher and

at 1800 fps this thing will penetrate quite well with a PROPER SOLID

bullet. It will not be a flat shooter, so keep your shots at game short.

quote:

Originally posted by Gerard:
Myth: More Sectional Density = Better Penetration

Well Gerard,

I was referring to YOUR solids. So at 1800 FPS with a S D over .350
and your design and construction, are you saying the penetration will
be in-adequate on elephant heads using your solids?

BigFiveJack,
I am saying that sectional density does not drive penetration. If one bullet has more SD than another, it does not follow that it will penetrate better. That is the myth. We have a number of FNs in the range where better terminal ballistics are possible with lighter bullets than with heavy bullets. That is the reason why we discontinued some of the heavier bullets in a couple of calibers. Both were tried and the repeat business was on the lighter bullet.

More Viking Law about sectional density and penetration:
There are no absolutes.

Sectional density drives overturning moment of long solid bullets, and makes them tumble too soon and penetrate less.

Sectional density drives expansion of softpoint/expanding bullets, putting the brakes on their penetration.

Momentum, nose shape, and material properties of bullet and penetrated medium (such as how they react to what velocity) are more important "drivers" of penetration than a mere static sectional density.
I smell coffee.

This is what happens to me when I think that

I know something. Some day I'll learn...

quote:

Originally posted by Gerard:
BigFiveJack,
I am saying that sectional density does not drive penetration. If one bullet has more SD than another, it does not follow that it will penetrate better. That is the myth. We have a number of FNs in the range where better terminal ballistics are possible with lighter bullets than with heavy bullets. That is the reason why we discontinued some of the heavier bullets in a couple of calibers. Both were tried and the repeat business was on the lighter bullet.

That is only the case if the lighter bullet has a higher velocity than the heavier bullet. If all else is equal I.E. caliber, nose shape, velocity etc. then the higher SD bullet will penetrate deeper.

465H&H

quote:

Originally posted by 465H&H:

quote:

Originally posted by Gerard:
BigFiveJack,
I am saying that sectional density does not drive penetration. If one bullet has more SD than another, it does not follow that it will penetrate better. That is the myth. We have a number of FNs in the range where better terminal ballistics are possible with lighter bullets than with heavy bullets. That is the reason why we discontinued some of the heavier bullets in a couple of calibers. Both were tried and the repeat business was on the lighter bullet.

That is only the case if the lighter bullet has a higher velocity than the heavier bullet. If all else is equal I.E. caliber, nose shape, velocity etc. then the higher SD bullet will penetrate deeper.

465H&H

My thinking was where 465's is!

I've fired 'em in my Ruger No.1 .45-70 "Improved" (long-throated). Five loads were shot starting at 60.5 grs of H335 and ending at 64.5grs. The last load produced 1885 fps. Now, that bullet was seated long, about the same as a .458WM, and I could have gone more, but I stopped there. No pressure signs and no blown primers!

The main problem, if there was one, was the 1 in 20" twist rate. At 100 yds it showed slight tipping.

And the barrel of that rifle is original at 22", except for the long throat (.30").

It's in my testing plans this year to try those 600s (has cannelure and RN)in my CZ 550 .458WM, seated long. I've no doubt that I can hit, or come close to the velocities shown in Barnes #3 for the Lott.

By way of further interest, Gayana in RIFLE No.248 wrote: "If you are hunting buffalo, then an appropriately constructed 600-grain soft is an entirely reasonable choice for a .458 Winchester magnum." And: "A 600-grain bullet at 1750 fps shoots plenty flat enough for buffalo hunting in all but exceptional circumstances."

And, for Ray's benefit: A bullet will not pop out the front of a case under recoil if it's not crimped. It might be pushed in, but not out! And only could it be pushed in if the powder charge was too light for providing a measure of compression. Under recoil, when the rifle is moving in reverse at around 20 fps, the cartridge is stationary until it is slammed by the FRONT of the magazine (in a magazine rifle). In a single-shot it doesn't matter. It may in some doubles before the second barrel is fired. That would make sense, but not in the other two scenarios.


Bob

www.bigbores.ca

quote:

That is only the case if the lighter bullet has a higher velocity than the heavier bullet.

Give me one logical reason why you would fire a light bullet at the same speed as a heavy one in the same cartridge.

quote:

If all else is equal I.E. caliber, nose shape, velocity etc. then the higher SD bullet will penetrate deeper.

You are right about the penetration, except that it is not the SD that makes it penetrate better, it is the momentum / cross section. Proof of that is that, if you take the high SD bullet and place it on a table next to the lower SD bullet, niether one will go anywhere, no matter if the SD is 4 on one and 2 on the other.

Taking a break now, back in two weeks.

quote:

Originally posted by Gerard:

quote:

That is only the case if the lighter bullet has a higher velocity than the heavier bullet.

Give me one logical reason why you would fire a light bullet at the same speed as a heavy one in the same cartridge.

quote:

If all else is equal I.E. caliber, nose shape, velocity etc. then the higher SD bullet will penetrate deeper.

You are right about the penetration, except that it is not the SD that makes it penetrate better, it is the momentum / cross section. Proof of that is that, if you take the high SD bullet and place it on a table next to the lower SD bullet, niether one will go anywhere, no matter if the SD is 4 on one and 2 on the other.

Taking a break now, back in two weeks.

One reason is that if you increase velocity with a lighter bullet it may not regulate in a double rifle. Usually, lighter bullets regulate best at the same velocity as heavier bullets but that is surely not an absolute.

It is much easier to understand SD then Momentum/cross sectional area. SD for most bullets is given by the manufacturer and as said above , it works. Now who would expect a bullet sitting on the table to have any thing including momentum. Remember I said all other things being equal and that includes velocity etc.

Higher SD = greater penetration (all things being equal) is anything but a myth.

465H&H

We'll have to bring this to Mass. Inst. of Tech. {M.I.T.} for

some physics doctoral students to experiment with.

(O.K. So. Cal. University students can likely do just as well.)

quote:

Originally posted by 465H&H:

quote:

Originally posted by Gerard:

quote:

That is only the case if the lighter bullet has a higher velocity than the heavier bullet.

Give me one logical reason why you would fire a light bullet at the same speed as a heavy one in the same cartridge.

quote:

If all else is equal I.E. caliber, nose shape, velocity etc. then the higher SD bullet will penetrate deeper.

You are right about the penetration, except that it is not the SD that makes it penetrate better, it is the momentum / cross section. Proof of that is that, if you take the high SD bullet and place it on a table next to the lower SD bullet, niether one will go anywhere, no matter if the SD is 4 on one and 2 on the other.

Taking a break now, back in two weeks.

One reason is that if you increase velocity with a lighter bullet it may not regulate in a double rifle. Usually, lighter bullets regulate best at the same velocity as heavier bullets but that is surely not an absolute.

It is much easier to understand SD then Momentum/cross sectional area. SD for most bullets is given by the manufacturer and as said above , it works. Now who would expect a bullet sitting on the table to have any thing including momentum. Remember I said all other things being equal and that includes velocity etc.

Higher SD = greater penetration (all things being equal) is anything but a myth.

465H&H

In my experience, the lighter bullets regulate at higher velocitites. And this follows reason since the rifle needs sufficient recoil to cause the barrels to describe their recoil arch, uncrossing their crossed static positions. If velocity were the same between heavier and lighter bullets, the reduced bullet weight and powder weight/ejecta would produce reduced recoil which - would also be slower - and cause the barrels to remain crossed at bullet exit from the muzzle - and the lighter bullet's faster acceleration exacerbates this problem as well, since it reduces barrel time.

In reality the lighter bullets need more and/or faster recoil to uncross in quicker time than with a greater weight but slower bullet, since the lighter bullet's greater velocity means less barrel time.

In the cases where I have heavier and lighter bullets shooting to regulation in the same rifle, though the lighter bullets have more velocity, they have less energy, which means they have less momentum as well since enegry calculation square velocity while momentum calculations do not.

As an example, from my 458wm double rifle, I have 500gr Woodleighs, softs and solids at slightly different velocities, 450gr North Fork solids and 350gr Woodleigh and Hornaday softs all shooting to regulation, with the 350's shooting just a bit higher poi. The energy calculations and so momentum calculations show that the added velocity required to get the lighter bullets shooting without crossing is insufficient to make up for the loss of weight. Energy calculations follow bullet weight, with the 500's having the most, then the 450's and then the 350's; velocity is inverse, 350's fastest, then 450's then 500's.

I suspect that if the bullets all had the same construction and profile the heavier bullet would penetrate deeper, and Gerard's comments and arguement actually support this theory, so far as double rifles are concerned, since enough velocity can't be added to the lighter to bring momentum up to or beyond that developed by the heavier bullets - and still have them shoot to regulation.

If the lighter bullet were to exceed the penetration of the heavier bullet, shape, construction, all but velocitiy and length equal, then it must be something else, perhaps spin rate/SF...

JPK

quote:

Originally posted by JPK:

quote:

Originally posted by 465H&H:

quote:

Originally posted by Gerard:

quote:

That is only the case if the lighter bullet has a higher velocity than the heavier bullet.

Give me one logical reason why you would fire a light bullet at the same speed as a heavy one in the same cartridge.

quote:

If all else is equal I.E. caliber, nose shape, velocity etc. then the higher SD bullet will penetrate deeper.

You are right about the penetration, except that it is not the SD that makes it penetrate better, it is the momentum / cross section. Proof of that is that, if you take the high SD bullet and place it on a table next to the lower SD bullet, niether one will go anywhere, no matter if the SD is 4 on one and 2 on the other.

Taking a break now, back in two weeks.

One reason is that if you increase velocity with a lighter bullet it may not regulate in a double rifle. Usually, lighter bullets regulate best at the same velocity as heavier bullets but that is surely not an absolute.

It is much easier to understand SD then Momentum/cross sectional area. SD for most bullets is given by the manufacturer and as said above , it works. Now who would expect a bullet sitting on the table to have any thing including momentum. Remember I said all other things being equal and that includes velocity etc.

Higher SD = greater penetration (all things being equal) is anything but a myth.

465H&H

In my experience, the lighter bullets regulate at higher velocitites. And this follows reason since the rifle needs sufficient recoil to cause the barrels to describe their recoil arch, uncrossing their crossed static positions. If velocity were the same between heavier and lighter bullets, the reduced bullet weight and powder weight/ejecta would produce reduced recoil which - would also be slower - and cause the barrels to remain crossed at bullet exit from the muzzle - and the lighter bullet's faster acceleration exacerbates this problem as well, since it reduces barrel time.

In reality the lighter bullets need more and/or faster recoil to uncross in quicker time than with a greater weight but slower bullet, since the lighter bullet's greater velocity means less barrel time.

In the cases where I have heavier and lighter bullets shooting to regulation in the same rifle, though the lighter bullets have more velocity, they have less energy, which means they have less momentum as well since enegry calculation square velocity while momentum calculations do not.

As an example, from my 458wm double rifle, I have 500gr Woodleighs, softs and solids at slightly different velocities, 450gr North Fork solids and 350gr Woodleigh and Hornaday softs all shooting to regulation, with the 350's shooting just a bit higher poi. The energy calculations and so momentum calculations show that the added velocity required to get the lighter bullets shooting without crossing is insufficient to make up for the loss of weight. Energy calculations follow bullet weight, with the 500's having the most, then the 450's and then the 350's; velocity is inverse, 350's fastest, then 450's then 500's.

I suspect that if the bullets all had the same construction and profile the heavier bullet would penetrate deeper, and Gerard's comments and arguement actually support this theory, so far as double rifles are concerned, since enough velocity can't be added to the lighter to bring momentum up to or beyond that developed by the heavier bullets - and still have them shoot to regulation.

If the lighter bullet were to exceed the penetration of the heavier bullet, shape, construction, all but velocitiy and length equal, then it must be something else, perhaps spin rate/SF...

JPK

I have only tried light bullets in my Searcy 470. They regulate at the same velocity as the 500 grainers. So much for a sample size of one.
Michael458, take note.
465H&H

465H&H,

quote:

One reason is that if you increase velocity with a lighter bullet it may not regulate in a double rifle.

If you switch brands of the same weight bullet, the double may not regulate. The solution is then to tune the regulation by varying col. The same applies to lighter bullets at higher speed. If they do not regulate, tune regulation with col. Regulation is no reason to shoot lighter bullets at the same speed as heavier bullets, it remains illogical.

quote:

Usually, lighter bullets regulate best at the same velocity as heavier bullets but that is surely not an absolute.

It certainly is not an absolute and, in 13 years of the use of lighter FNs in doubles, regulation of lighter bullets at logically higher speeds has not been an issue.

quote:

It is much easier to understand SD then Momentum/cross sectional area.

In motoring, horsepower is easier to understand than power to weight ratio. That does not mean that the car with the most horsepower will accelerate faster than a car that has less horsepower but a better power to weight ratio.

quote:

SD for most bullets is given by the manufacturer and as said above , it works.

Horsepower is given by most manufacturers and, like SD, it is a number that may be used in further calculation. SD is also only usefull when used in further calculation and does not always translate to better penetration.

quote:

Now who would expect a bullet sitting on the table to have any thing including momentum.

My point exactly. Two bullets sitting on a table do not go anywhere, despite the fact that both have SD values. They do not go anywhere because they have no momentum. That is a good example of the fact that SD does not drive penetration, momentum/cross section does.

quote:

Remember I said all other things being equal and that includes velocity etc.

Therein lies the problem. SD/penetration arguments are always qualified with "all things being equal" and, in reality, all things are never equal.

quote:

Higher SD = greater penetration (all things being equal) is anything but a myth.

This is true but, remove the "all things being equal", because it never is, and SD = penetration remains a myth.

quote:

I have only tried light bullets in my Searcy 470. They regulate at the same velocity as the 500 grainers. So much for a sample size of one.

Again my point exactly: You appear to base your opinion on this one sample of one. Try a couple more examples with different rifles and bullets and the results will become very confusing. Only when you have a couple of dozen examples will a pattern emerge. That pattern will not support regulation of light bullets at the same speed as heavier bullets.

quote:

Michael458, take note.

Michael458's work is a good example of what I am saying. Take any one or two of his samples (picked selectively) and you can prove any one of several opposing theories. Take any ten or so of his examples (picked selectively) and the results seem confusing but, take the entire body of work and a clear pattern emerges.

Gerard,

If you say that there are more than one way to increase penetration such as adding velocity, changing nose shape, reducing bullet diameter etc. then I agree with you but that doesn't negate the fact that increasing SD will also increase penetration. The easiest and cleanest way to measure the affect of any one variable is to standardize all other variables. Yes, there are multi-variate statistical techniques to measure multiple variables but that is a much more complicated test.

To say that SD has no affect on penetration is pure bull. Compare the penetration of the .458 diameter Woodleigh 550 grain solid with the Woodleigh 500 grain solid 2,150 vs 2,250 fps respectively on elephant and there is no doubt about it. I have done it and the differences were dramatic.

465H&H

465H&H,

quote:

To say that SD has no affect on penetration is pure bull. Compare the penetration of the .458 diameter Woodleigh 550 grain solid with the Woodleigh 500 grain solid 2,150 vs 2,250 fps respectively on elephant and there is no doubt about it. I have done it and the differences were dramatic.

That is more than one variable - varying weight and varying speed.

However, a 550gr Woodleigh solid at 2150fps has more momentum than a 500gr Woodleigh solid at 2250. That is why it will go deeper, not because of the extra weight.

Take the same scenario and stay with only one variable - speed. Two 550gr Woodleigh solids, one going at 2150fps and one going at 2250fps. Which one will go deeper? Same Sd but one will go deeper than the other. How do you explain that?

Gerard,

Get back to the case in point and quit going off on tangents. As I said SD isn't the only variable that affects penetration. All else being equal a bullet with higher SD will penetrate deeper than a bullet with less sectional density. Case closed.

465H&H

465H&H,

quote:

Get back to the case in point and quit going off on tangents.

Forgive me if I confuse easily. You want "all to be equal" in a comparison with only one variable. Then you give an example that proves your point, but your example has two variables. I give an example with only one variable and ask which one will go deeper. How is that going off at a tangent? How about telling us which one, in my example, in your opinion, will go deeper.

quote:

As I said SD isn't the only variable that affects penetration. All else being equal a bullet with higher SD will penetrate deeper than a bullet with less sectional density.

Ok, take an "all else equal" comparison as you see it, where speed, construction, target medium and "all else is equal", just the SD of the two bullets differ.

Let's use your 550gr and 500gr Woodleigh solids, both at 2150fps.

The 550gr bullet has more momentum and kinetic energy than the 500gr bullet and immediately this is not an equal situation. Apart from the fact that "all else equal" is now no longer so, do you ascribe the deeper penetration of the 550 to the extra weight, the extra energy or the higher momentum?

The only scenario in which all can be equal, with only the SD of two bullets different, is when they are stationary - In which case penetration is equal at zero. This proves conclusively that more sectional density does not improve penetration. There is an upside to this. It also proves that less SD does not improve penetration. Just that SD is irrelevant to penetration depth.

quote:

Case closed.

I'm afraid not. You need to give logical explanations to the scenarios above before it can be closed. Until then, SD = penetration is a myth.

quote:

The only scenario in which all can be equal, with only the SD of two bullets different, is when they are stationary - In which case penetration is equal at zero. This proves conclusively that more sectional density does not improve penetration. There is an upside to this. It also proves that less SD does not improve penetration. Just that SD is irrelevant to penetration depth.

Gerard, with all due respect that is the silliest argument that I have ever heard.

If you take two bullets of equal weight and diameter and place them on the same table. One is a GS Custom FN solid and the other is a RN steel jacketed solid, which will penetrate further? That proves that FN solids do not penetrate better than RN solids. or: Place two like bullets on the table except that one is of larger diameter than the other. Which will penetrate further? That proves that bullet diameter does not affect penetration. or: place two nothings on the table and drive one at 2,000 fps and the other at 3,000 fps. Which one will penetrate further? That proves that higher velocity doesn't increase penetration.

How about taking two bullets of the same weight at the same velocity, one a soft point and the other a solid. Both have the same momentum. Which will penetrate farther? The answer is obvious. Using your logic, that shows that momentum does not affect penetration.

You are correct in that my example wasn't completely equal as regards velocity being equal in the above example of 500 and 550 grain bullets. But and this is a big but, the heavier bullet was handicapped by a lower velocity and still out penetrated the lighter bullet because of its higher SD.

Again with all due respect, you put your self in a corner with the statement that SD does not affect penetration, it's time to admit you are wrong. Until you do there is no sense in us continuing this discussion.

465H&H

Respect you guys both, but you need to get in a ring or get a room ... The original post was about loading a 600g Barnes bullet in a 458 Win Mag. Can we get back on topic?

Regards,

Chuck

quote:

Originally posted by 465H&H:
Gerard,

Get back to the case in point and quit going off on tangents. As I said SD isn't the only variable that affects penetration. All else being equal a bullet with higher SD will penetrate deeper than a bullet with less sectional density. Case closed.

465H&H

the best reason to use SD is to know if the bullet is heavy enough, ~.3+ for cup and core, about ~.27+ for brass/copper monometals, After that SD is used to have a comparisson between bullets of the same weight and construction.

Andy, a 550 gr vs a 500gr basicaly can't EVER be "AEBE", because its not, especially in a 458 winmag. the winmag CANNOT throw the 550gr bullet, and certainly not the 600, 2150fps. So, now the scenero morphs to a 458 lott shooting both at 2150 .. but wait a second, we've now broken the context of AEBE, as we had to change case to "get there"

okay, fine, 600, 550, 500gr .458 bullets going 2150 ... assuming aalf-hsed reloading, you still have pressure differences .. again, it aint AEBE

but lets go on and play along .. what happens when the 600, 550, and 500gr bullet hit, won't it be obvious that the 600 will penetrate further?

NO!
its NOT obvious.

600gr bullet is the barnes original .. SOFT, unbonded, and 2150 might be outside its performance envelope .. highly likely to over expand and not penetrate deeply, DUE TO DESIGN

550 woodliegh.. wait, did we say soft or solid..
2150, very likely to hold together and penetrate well. Welded (soldered/bonded) core, soft or solid ... let's compare it as softs, just to keep it fair with the 600gr barnes original

500 hornady interlock .. oh, wait, that's different.. so what, the first 2 are different, and the only makers of those particular bullets

famous for being far too soft, and over expanding ... but its a classic .458 bullet, and one likely finds these in the reloading room. probably penetrates better than the 600, unlikely to do more than the 550,,,, can't argue if you are a SD fan (which I kind of am) that it won't penetrate better than the 550gr at the same speed.

so, AEBE, the 458 winmag CAN'T run a 600gr at 2150.

and also AEBE, EQUAL, then one must run them all the same SPEED ..

and since your are using a barnes original in THIS THREAD, and no one else makes a 550, then its inherently impossible for AEBE

But if there was (and there aint) 600, 550, and 500gr barnes originals, SD would give you a relative comparison of how those would penetrate.

but changing construction changes EVERYTHING.

in a nutshell, only in the false condition that its even POSSIBLE to make everything else equal, WOULD (but doesn't) SD allow you to compare across maker's bullets.


I am also not satisfied with Gerard's MO/MX setup ... but it does work in the real world.

you aren't arguing FOR a standard of comparison of pentration in media NOW are you?

Chuck,
We are on topic. It was said that a 600gr bullet in 458 has high SD and that as a result it will penetrate well. That is what we are discussing.


465H&H,
Excellent examples all.

quote:

If you take two bullets of equal weight and diameter and place them on the same table. One is a GS Custom FN solid and the other is a RN steel jacketed solid, which will penetrate further? That proves that FN solids do not penetrate better than RN solids.

Now we are getting somewhere. You are absolutely correct. Taken in isolation, without considering a number of co-related factors, bullet construction means nothing. You have to add the right amount of spin for correct stability, forward motion to generate energy and momentum and so on.

quote:

or: Place two like bullets on the table except that one is of larger diameter than the other. Which will penetrate further? That proves that bullet diameter does not affect penetration.

Right again. Caliber can be as big or as small as you like. It means nothing in isolation. You must add energy, momentum, bullet construction and a host of factors that determine the outcome of external and terminal ballistics.

quote:

or: place two nothings on the table and drive one at 2,000 fps and the other at 3,000 fps. Which one will penetrate further? That proves that higher velocity doesn't increase penetration.

Perfect reasoning. Just comparing velocity, on its own, without the correct construction, the correct weight that will result in good dimensional parameters and a balance between static and dynamic stability, momentum and energy, is useless.

quote:

How about taking two bullets of the same weight at the same velocity, one a soft point and the other a solid. Both have the same momentum. Which will penetrate farther? The answer is obvious. Using your logic, that shows that momentum does not affect penetration.

You give an excellent example of how a simplistic argument like "higher sd increases penetration" cannot hold water. There are always a multitude of factors that must be considered to bring about the desired result in terminal ballistics.

quote:

You are correct in that my example wasn't completely equal as regards velocity being equal in the above example of 500 and 550 grain bullets. But and this is a big but, the heavier bullet was handicapped by a lower velocity and still out penetrated the lighter bullet because of its higher SD.

Not because of the higher SD, because it has more momentum. Higher SD, in this case, increased the Mo/Xsa. The same advantage can be gained by driving the lighter bullet faster and thus increasing Mo/Xsa. One could also decrease the diameter and thereby increase Mo/Xsa. There are many ways to skin a cat and SD, seemingly, is but one of them. Unfortunately SD wears a mask and takes credit where it is not due.

quote:

Again with all due respect, you put your self in a corner with the statement that SD does not affect penetration, it's time to admit you are wrong.

If penetration is tied to SD and I am wrong, how do you explain:

1. Two 550gr Woodleigh 600gr Barnes solids, identical SD, one going at 2150fps and one going at 2250fps. Which one will go deeper? (The faster bullet goes deeper, despite the fact that SD of the two are identical.)

2. Two solids of identical construction type and .458" caliber, one is 500gr (SD = .341) going at 1700fps and one is 300gr (SD = .204) going at 3000fps. Which one will go deeper? (The difference in penetration depth is statistically insignificant. They go to the same depth in tissue and tissue simulant, despite the fact that one has an almost 70% SD advantage. We used a 45-70 and a 460 Weatherby to arrive at this result.)

3. Two 200gr bullets, same caliber, identical SD, same speed but one a soft and one a solid. Which one will go deeper? (You have already admitted that, despite identical SD values, one will penetrate better than the other.)

4. Will a bullet with higer SD than another always penetrate better than the other? (Of course not.)

5. Will a bullet with lower SD than another always penetrate less than the other? (Of course not.)

quote:

Until you do there is no sense in us continuing this discussion.

I have to admit that I am wrong and agree with you, before you will continue the discussion in which we have differing opinions? Does this mean that if I support SD = Penetration, you will oppose it?

The bottom line is:
The only argument SD proponents can bring to the table is that higher SD will increase penetration, when all else is equal. On the surface this seems true. Upon closer inspection, it is the increased Mo/Xsa that gives the increased penetration.

The simple experiment is to vary the Mo/Xsa and see how penetration depth follows it and then to vary SD and see how penetration depth does not follow it.

Jeffe,
You are right about Mo/Xsa. As speed increases, AEBE, there are factors that work against the increase in penetration being linear with the increase in speed. At extremes it does not work but on middle ground, as we have here, most examples will hold water. Enough to show that SD does not drive penetration, anyway.

I'm being lazy but could someone define Mo/Xsa?


Thanks!

from: huntersboma.co.za/RankingCART.pdf


Mo/Xsa - a yardstick for judging penetration capability

Which projectile, made from brass, would penetrate the deepest when shot at the same velocity:
a) a round ball weighing 300 grains - featuring poor SD or
b) a bullet weighing 300 grains - featuring better SD ?

The latter, as we put more weight behind its frontal area and the XSA is smaller.
The ratio of momentum (the force) over cross sectional area (Xsa) is the best predictor of penetration
ability we have. Mo/Xsa - the higher the number, the better the penetration. It is a question to balance
the force applied (momentum) to the resistance by virtue of expanded frontal area of the bullet.
The ratio of Mo/Xsa is equal to the Velocity x SD.

(m x v)/A = (m/A) x V

Where m is the mass of the bullet, v is its velocity, and A is its cross sectional area.

Thanks Jim!

There are several ways to estimate a penetration index. In addition to the one given above, here is one that is commonly used by balistic experts.

Penetration Index & Energy

See A.B.Alphin, Any Shot You Want, On Target Press 1996



About Penetration Index
The penetration index is calculated by dividing kinetic energy with the frontal area of the bullet and multiplying the result by the sectional density, as described by A. Alphin.

If you simplify the formula, you will find that the fundamental relation is proportional to the momentum divided by the area. The actual numerical value is squared, divided by 2 etc.to make the numbers better reading.

This number, called "momentum density" is a basic value calculating the penetration in solid materials of nondeforming projectiles etc. including HEAT warheads and the like.

This is an improvement on the older momentum theories, but for penetration in game you have to take into account the stability in aqueous media. For this read the chapter on the SuperPenetrator.

Conclusion
Penetration Index smaller than 85: doubtful, not recommended for head shots on elephant. PI between 85 and 100: just suitable. PI between 100 and 120: well suited for head shots. 120 to 130: very reliable. More than 130: absolute top values for big game cartridges, red highlighted.

The PI is a valuable figure to compare the relative penetration ability of non-deforming bullets for a given medium. It has nothing to do with killing power or knock down ability or other, most useless figures given in literature. It is a relative figure and not linearly correlated to the penetration depth in a target. That means a bullet with PI of 70 travels not half the way of one with a PI of 140. The real ratio depends on the energy dissipation on the way through the target. It is impossible to calculate the penetration depth in an animal by theoretical figures.

You will notice that SD is an interagral part of both Indecies.

465H&H

quote:

Originally posted by 465H&H:
See A.B.Alphin,

how about NO

quote:

Originally posted by 465H&H:
Conclusion

this is a misdirection and IRRELEVENT to the discussion at

quote:

Originally posted by 465H&H:
...head shots on elephant.

not relevent to 600gr barnes originals, and just hotair .. i HOPE to never shoot an elephant, as it would mean i have done something massively wrong .. 99.999% of hunters never dream of it. go to AFRICAN HUNTING if you wish to blather on about shooting elephants, no one cares

quote:

Originally posted by 465H&H:
relative penetration ability of non-deforming bullets for a given medium.

which is irrelevent from the subject of 600gr barnes originals. this is yet another attempt to twist it back into something the discussion isn't about

quote:

Originally posted by 465H&H:
It is impossible to calculate the penetration depth in an animal by theoretical figures.

then stop faffing on about it

quote:

Originally posted by 465H&H:

You will notice that SD is an interagral part of both Indecies.

which are, as you stipulate

quote:

Originally posted by 465H&H:
It is impossible to calculate the penetration depth in an animal by theoretical figures.

quote:

Originally posted by 465H&H:


465H&H

SD is only relevent for
like calibers
like construction
in a small window of speeds
and it CERTAINLY doesn't do JACK comparing nonexpanding bullets at realistic speeds and pressures to an expanding unbonded cup and core SOFT bullet.

impressing those who don't know to ask enough questions to find out why.

SD, it self, has a huge assumption that you are comparing LIKE construction. No one if foolish enough to state, at a hunting speed, 2150, that a 600gr cup and core purelead and pure copper unbonded bullet is going to penetrate NEARLY as well as a 500gr FN copper solid, also going .458 and of the same diameter.

you are in a hole, sir, stop digging

I have quit using the Penetration index given by Alphin and others after reading Michael458`s tests of different bullets and calibers.. Seems that even when using the same bullet (Barnes Banded Solid) a heavier, large diameter bullet (like the .458" 500 grs or the .510" 570 grs) will penetrate a lot deeper than a similar 338" 250 grs bullet at higher speed - EVEN THOUGH THE .338" BULLETS TESTED HAD A MUCH HIGHER PENETRATION INDEX VALUE...

The 600gr bullet is to much for 458 win mag.

I believe the original post said he wanted to try it. May just be tinkering? Made no mention of hunting with it.
There are some folks on this forum that like to shoot but do not hunt.
????

quote:

Originally posted by jro45:
The 600gr bullet is to much for 458 win mag.

quote:

Originally posted by jeffeosso:

quote:

Originally posted by 465H&H:
See A.B.Alphin,

how about NO

quote:

Originally posted by 465H&H:
Conclusion

this is a misdirection and IRRELEVENT to the discussion at

quote:

Originally posted by 465H&H:
...head shots on elephant.

not relevent to 600gr barnes originals, and just hotair .. i HOPE to never shoot an elephant, as it would mean i have done something massively wrong .. 99.999% of hunters never dream of it. go to AFRICAN HUNTING if you wish to blather on about shooting elephants, no one cares

quote:

Originally posted by 465H&H:
relative penetration ability of non-deforming bullets for a given medium.

which is irrelevent from the subject of 600gr barnes originals. this is yet another attempt to twist it back into something the discussion isn't about

quote:

Originally posted by 465H&H:
It is impossible to calculate the penetration depth in an animal by theoretical figures.

then stop faffing on about it

quote:

Originally posted by 465H&H:

You will notice that SD is an interagral part of both Indecies.

which are, as you stipulate

quote:

Originally posted by 465H&H:
It is impossible to calculate the penetration depth in an animal by theoretical figures.

quote:

Originally posted by 465H&H:


465H&H

SD is only relevent for
like calibers
like construction
in a small window of speeds
and it CERTAINLY doesn't do JACK comparing nonexpanding bullets at realistic speeds and pressures to an expanding unbonded cup and core SOFT bullet.

impressing those who don't know to ask enough questions to find out why.

SD, it self, has a huge assumption that you are comparing LIKE construction. No one if foolish enough to state, at a hunting speed, 2150, that a 600gr cup and core purelead and pure copper unbonded bullet is going to penetrate NEARLY as well as a 500gr FN copper solid, also going .458 and of the same diameter.

you are in a hole, sir, stop digging

Jeffe,

You are certainly in a snit this am. Didn't your Viagra work last night? Don't take offense, just joking.

I think you need to reread my posts as you obviously missed something. As I said "all other things being equal, the bullet with higher SD will penetrate further than one of lower SD.". so we are saying he same thing. Your comparison of .338 with 458 diameter bullets violates this assumption as the bullet diameter is not equal. But then again how do you explain the 9.3 bullets doing so much better than many of the favorites in Michael's tests?

Maybe you are not interested in hunting elephants but that is exactly why most of the calibers we are talking about were invented and I suspect that there are more posters on here interested in finding the right bullets for hunting dangerous game than shooting bullets in to test media, but that doesn't decrease the importance of testing.

As far as taking the thread off subject, I think the posters original question was fully answered before we went off thread. The ones who took it off thread originaly were those that said SD has no relationship to penetration.

By the way the .458 500 grain bullet has a SD of .341 to the .338 250 grain bullets .313.

465H&H

you are right, I am being a jerk .. though that's the mode, not the message.

if AA told me the sun rises in the east, i'd go check it the next morning

quote:

Originally posted by jeffeosso:
you are right, I am being a jerk .. though that's the mode, not the message.

if AA told me the sun rises in the east, i'd go check it the next morning

I try to do the same and keep an open mind. If someone comes up with a good reason for me to change my mind, I am more than willing.

465H&H

quote:

Originally posted by 465H&H:
Your comparison of .338 with 458 diameter bullets violates this assumption as the bullet diameter is not equal......


..By the way the .458 500 grain bullet has a SD of .341 to the .338 250 grain bullets .313...

465H&H

I was the one - not Jeffe..
My point was not related to SD at all. Just to Alphins Penetration Index.
In Michael458`s test of the 250 grs Barnes Banded Solid in 338 that bullet in the 338 Ultra Mag had significantly higher value in the penetration index because of high vel and a SD of .313

My point was that the penetration index is proved useless by Michael because a .510" / 570 grs Barnes Banded at around 2200 f/s or a 500 grs .458" Banded solid at similar velocity (both have significantly less penetration index values compared to the 338 banded solid mentioned above) both penetrate further than the 338.. And the 338 and the 458/510 solids in question all have the same meplat/diameter ratio..

Nothing about SD here just that Michael proved the PI wrong in real life..
Maybe if we are talking about penetration steel / hard objects it makes sense, I dont know??

"All things being equal" is NEVER EQUAL and EVERYONE is in a snit here...You're ALL in that "prove a position" position.

About all you all can say is under ONE circumstance ONE bullet did ONE thing...There is no way you can say that translates to the next scenario other than the probability of "this" happening is "X" percent.

No two animals are killed under exactly the same conditions, and splitting hairs over "momentum", SD difference between 100 and 150, or a hundred fs gets into the ludicrous end of the spectrum. There are so many variables involved in this particular argument and killing game as to make all these presentations nothing but pecker waving, and all the jumping around isn't proving anything other than the testosterone getting out of all proportion.

There is ample evidence that certain bullets do certain things and the time for experimentation, conjecture, splitting hairs, redefining the concept of the Universe is NOT when you're pranging a cranky beasty...if you're smart enough.

It would really be nice...SOMETIME...if all those with all that experience would act in concert and present that wealth of information in some form OTHER than confrontational...ya'all seem to have a brain phart at the slightest whiff of difference.

I'D like to read of some of that experience outside my present experience, then let ME decide which and what...just in case I have a windfall and CAN go hunting something I haven't yet and need good advice...all that hooting and hollering just hurts my ears and doesn't tell me much at all.

Luck

FOOBAR,

You make some excellent points. But, I don't think that most of are driven by testosterone levels on these posts. Most of us are just trying to understand why things happen the way they do and to try to get some perspective on how a bullet will react so that we can make an intelligent chosen for our next DG hunt. When someone does make a statement that we feel is obviously false and could lead to someone making the wrong choice, I think it is our duty to rebut that statement in as courteous manner as possible.

At the end of the day sometimes we just need to agree to disagree.

465H&H

Oh ya, i tryed 68gr of RL15 under a 600 Barnes and got 1800fps and no signs of any pressure. After the big bore shoot saturday i'll load some more up working up a grain at a time and see how it does.

My 458 dosnt particularly like 500 grn solids. I see no use for the 600 in this cal except as a toy to play with and lerarn from. There are many wo might disagee with me but I find a 450grn bullet of most styles to perform the best. Speed, Mass, design and load compression or not all play a part. 458 450 fn solid at 2200 to 2400fps perfect for this chambering. You want to use the 800grn go to a 500 or 505.

quote:

Originally posted by buffalo:

quote:

Originally posted by 465H&H:
Your comparison of .338 with 458 diameter bullets violates this assumption as the bullet diameter is not equal......


..By the way the .458 500 grain bullet has a SD of .341 to the .338 250 grain bullets .313...

465H&H

I was the one - not Jeffe..
My point was not related to SD at all. Just to Alphins Penetration Index.
In Michael458`s test of the 250 grs Barnes Banded Solid in 338 that bullet in the 338 Ultra Mag had significantly higher value in the penetration index because of high vel and a SD of .313

My point was that the penetration index is proved useless by Michael because a .510" / 570 grs Barnes Banded at around 2200 f/s or a 500 grs .458" Banded solid at similar velocity (both have significantly less penetration index values compared to the 338 banded solid mentioned above) both penetrate further than the 338.. And the 338 and the 458/510 solids in question all have the same meplat/diameter ratio..

Nothing about SD here just that Michael proved the PI wrong in real life..
Maybe if we are talking about penetration steel / hard objects it makes sense, I dont know??

buffalo,

The penetration indices do not take all variables that affect penetration into count. For instance nose shape and twist rates also affect penetration and they are not included. Before we can say the index doesn't work, we must be assured that other variables not accounted for are not at work. I haven't followed Michael's experiment with these calibers as I don't have much interest in the .338 calibers. I seem to remember though that the 9.3 320 grain RN solid out did both of these calibers. I suspect that there are other factors at work here that haven't been accounted for. Even Michael has been at a loss to explain why this occurred. It just shows that we are still at the beginning of the learning curve on what affects penetration.

465H&H

U r right Walt, but the 570 grs Banded solid in .510" did as well as the 320 woodleigh in 9,3mm, but yes - many variables here, incl twist rate.. I just do not use the PI index anymore because it is proved wrong also by myself. On multiple shots on elephants postmortem I - as well - found out, that FN solids ( I used Barnes Banded and GS Customs) in 375,416 and 585 caliber penetrated as well OR better a 2200-2400 fps compared to 2600-2800 fps. For example - a very mild loaded Barnes Banded 750 grs in my 577 Tyrannosaur at 2150 fps totally outperformed a 300 grs .375 Barnes Banded at 2600 fps on ele bodyshots..
According to Alphins PI it shouldnt be so... But reality prooved something else - at least in the rifles we tested...

Ok, as far as Penetration Index goes, I'm shooting 570g Barnes Banded Solids and TSX's at 2400 fps. It has a measly PI of 112. The 500 NE shooting the same bullet at 2150 only has a PI of 90. My question: since I believe the 500 NE has a good reputation as an elephant stopper, can I throttle my 500 Jeffery down to 2300 fps and still be pretty confident that penetration will be more than adequate if I use Barnes Banded solids where solids are required (elephant) and TSX's where they're not (cape buffalo first shot, Alaskan brown bear), or should I stick with my 2400 fps load which shoots as well but comes back a bit quicker recoil wise...

Regards,

Chuck