Some help requested from the experts, what is the penetration index for .458 in 450grains@2280 fps?
http://www.grosswildjagd.de/penetr2.htm

I thought you bought a copy of my book.

...quit screwing around with 450gr bullets in the .458WM; 500gr @ 2150fps is adequate for anything that walks on four legs.

He's probably wondering about the 450 gr. monos.

He also probably didn't hoard all the 500 gr Speer AGS bullets like you did.

quote:

Originally posted by tsibindi:
...quit screwing around with 450gr bullets in the .458WM; 500gr @ 2150fps is adequate for anything that walks on four legs.

450 North Fork flat nose solids - sadly at least temporarily unavailble - at 2200fps will out penetrate the 500gr Woodleighs by a huge margin.

The remaining best choice for the 458wm is GS Custom flat noses in 450grs.

JPK

quote:

Originally posted by Will:
I thought you bought a copy of my book.

Well, I did. And I thought it was a good book until now. It's somewhere around here. but I don't have it memorized.
Yeah, I've got some 450 gr Barnes monos, but no double to shoot them out of just a "CRF bolt action". Also have a box of Speer Nitro 500 gr African solids with the tungsten core!
PAC ele coming up in Botswana, too.
Ask the experts for an opinion, and what do ya get?

Will actually be using a 470 double with GS FPS as primary and the 458 winnie will probably be the "light" rifle, although a 375 with 350 gr solids (RN)or 300gr NF FPS is also an option as back-up. Wonder which would be better on ele--375 350 gr RNSolids or 300gr NF FPS? I think the PI is going up significantly as the caliber goes down.

You can't compare PI of two different types of bullets (Woodleighs vs. GS), only the same type (brand) of bullet.

All else being equal, the 350 gr. would penetrate more than the 300 gr. bullet, but 350 gr. Woodleigh vs. 300 gr. GS or NF, who knows?

quote:

Originally posted by Will:
You can't compare PI of two different types of bullets (Woodleighs vs. GS), only the same type (brand) of bullet.
YUP

All else being equal, the 350 gr. would penetrate more than the 300 gr. bullet, but 350 gr. Woodleigh vs. 300 gr. GS or NF, who knows?

Maybe somebody knows.


I went ahead with the calculations and got an RPI of 91 for the 450gr 458@ 2280fps (vs 100 for the 500gr @2150).
The flat point solids are obviously the way to go most of the time, but that 375RN Solid in 350gr will probably drill a long way.

quote:

went ahead with the calculations and got an RPI of 91 for the 450gr 458@ 2280fps.

I am not one who takes calculations seriously when it comes to this sort of thing.

I bet if you shot 10 rounds into 10 different animals you will get 10 different penetration distances

Just make sure the shortes is long enough to kill whatever you are hunting.

quote:

Originally posted by Saeed:

I am not one who takes calculations seriously when it comes to this sort of thing.

I bet if you shot 10 rounds into 10 different animals you will get 10 different penetration distances

Just make sure the shortes is long enough to kill whatever you are hunting.

Saeed, with your rifles and bullets, I would imagine penetration is usually no problem.

quote:

Originally posted by Saeed:

quote:

went ahead with the calculations and got an RPI of 91 for the 450gr 458@ 2280fps.

I am not one who takes calculations seriously when it comes to this sort of thing.

I bet if you shot 10 rounds into 10 different animals you will get 10 different penetration distances

Just make sure the shortes is long enough to kill whatever you are hunting.

The PI is only a means of looking at relative penetration, not actual. Or, so the theory says.

Since all the loads listed have more than enough penetration for elephant and probably too much for buff in a herd situation, why worry?

465H&H

I have had some ele head shots using 458 win 500 gr sledgehammers that I wished had penetrated more. Part of the problem was a short barrel, but none of these loads guarantees complete head penetration on every ele from every possible angle. Relative Penetration Index, and the values assigned by Art Alphin, is a decent way to compare likely penetration effectiveness.

SGraves155,

Did you have enough penetration to kill the elephant or did you have not enough to kill it? Some people are only happy if the bullet exits the head on the opposite side. IMHO that is unessesary as the bullet only has to completely penetrate the brain from any reasonable angle. I doubt any bullet will give enough penetration if the tusk socket or a tooth is hit on the way to the brain.

465H&H

465H&H

The shot that comes to mind is one that missed the brain, and got stuck in the first vertebra about halfway thru. I believe that another few inches of penetration would have made a difference on that particuliar shot by likely breaking that vertebra. The elephant was killed with body shots.

/

SGraves155,

The Atlas and Axis are the two vertebrae closest to the skull. In elephant they are the heaviest and most dense of all vertebrae. They are very difficult to penentrate for any bullet. In fact Dan McCarthy records one 570 grain .500" GS FN solid that was stopped by them after only 31" of penetration on a frontal brain shot. IMO a bullet must not only penentrate one of these vertebrae but also destroy the spinal cord to kill an elephant. A solid bullet will not likely break these vertebare but drill a hole through them, at best causing temporary paralysis. A lot also depends on how much tissue and bone the bullet encounters before it gets to these vertebrae. On a frontal shot where the head is held high the bullet may have to penetrate 3 or more feet of trunk before it even encounters the head proper.

465H&H

quote:

Where they do have validity is in non visco-elastic solid material penetration by penetrators. Here penetrator shape does not influence in target behaviour.

Alf,

Not true. Refer to the penetration of monometal FN, RN and FMJ RN solids in the copy of my penetration tests I sent you last year from the LaGrange stop box.

The wood boards are as you say, "A non visco-elastic solid material."



Pictured 465 grain TCCI (A-Square) and 450 grain North Fork FN recovered from elephant skull.

Penetration in wooden boards was actually closer to that in elephant skull than water which greatly exagerated the penetration of the FN but accurately predicted the unstability of the RN.

SGraves155,

The fast 458's out penetrated the 375 in my tests (69-71 boards), but the 375 out performed the 458 win mag 61 1/2 boards compared to 58 boards.

You sound well equipped with any of your choices, but some more interesting than the others (the 350 grain 375 is interesting)!

Andy

After testing many calibers from 5.45 x 39 to 450 Dakota, my take on the Penetration Index and La Grange Stop-Box.

THE LA GRANGE STOP-BOX.

I know from personal experience that a monolithic FN out performs a similar RN on elephant by a margin of >1.6:1. But this in no way diminishes the significance of the La Grange stop-box. The stop-box accurately measures kinetic energy (KE) divided by unit of frontal area which defines penetration. This is extremely useful for hunters comparing the relative penetration of similar bullets of different weight or calibers.

PENETRATION INDEX.

For instance, a high velocity .458 will typically penetrate 69 – 71 1/2 boards depending on rifling twist. Factory Remington or Federal .458 Winchester ammo will penetrate just 58-59 boards. A 375 H & H at 2,570 fps will penetrate 61 boards. A .416 with custom 1-10 inch quick twist barrel will equal the penetration of the high velocity .458’s. A 450 Dakota shooting the 400 gr Barnes RN will perforate just 54 boards, or 23% less than a 500 gr. FMJ-RN. The 450 gr. Barnes RN perforates 62 boards and looses just 10% penetration compared to the 500 gr. FMJ. It is interesting to note that the 375 H and H, which has a similar velocity and sectional density (SD) as the 450 grain Barnes in a 450 Dakota, has nearly identical penetration. The same is true of the .416 and high velocity .458’s. A 450 gr. TC-FN or RN-FN penetrates 47 – 52 boards and loses 16 - 23% penetration compared to a similar RN in a hard rather than aqueous medium. With just two exceptions, these results closely coincide to Art Alphin’s simple “Penetration Index†(PI), KE divided by FA x SD.

The 400 grain .458 had almost 20% less penetration than the PI would indicate. The .375 Improved had slightly less than predicted. The other bullets were less than or equal to +/-10% of what the PI predicted. This demonstrates how very important it is to test unconventional bullet weights or designs prior to actually hunting with them. The stop-box demonstrates that the percentage of a bullets energy which comes from mass probably influences penetration more than simply multiplying by its SD. As Duncan McPherson demonstrated in his influential book, Bullet Penetration, calculus is necessary to closely predict penetration. However, the PI modeled empirical results much more closely than energy or momentum alone, or either the Taylor or Hatcher Knock Out values.

If you add the combined penetration of pine boards and air space, these bullets are penetrating 6 ½ to 8 ¾ feet. The depth of the boards by themselves equals 43 ½ inches for the .458 Winchester to 53 inches for a high velocity .416 or .450 Dakota. This is not too far off actual results on elephant using FMJ-RN bullets, and certainly explains why La Grange adopted the stop box to test elephant guns. The higher penetration bullets are probably adequate to perforate (exit) an elephants skull from any angle.

The physics of penetrating solids and liquids are substantially different, greatly complicating the ability of hunters to accurately predict the penetration of both RN and FN bullets in the same test medium. Future research should probably use a gelatin based test medium with a higher than normal specific gravity that is calilbrated to Dan McCarthy’s data.