I was "raised" to believe that a sectional density or .300 was the minimum for a bullet to be used for dangerous game, both in solids and softs. For example, the 9.3x62 at 286 grains and the .375 H&H at the same weight had SD's of .305.... as does the 450 grain .458 bullet.

With modern technology, i.e., monometal bullets and bonded cores (that shed little or no weight) and that weren't available in the past, is a SD of .300 still a valid guideline...

As a personal aside, I used 270 grain Barnes X's on Buffalo a couple of years ago and got shoot throughs except on the most extreme quartering angles (and those got to the vitals, just fine). They seemed to penetrate as well as my Speer tunsten solids.

There's a great tool for sectional density calculation at the Bear Tooth Bullets site, btw.

I've found that Barnes X and similar bullets will out penetrate conventional expanding bullets, even using low s.d. I've penetrated lengthwise on elk with a 200 Gr. X from a 35 Whelen and had similar results with a 250 Gr. Grand Slam.

I believe that the conventional wisdom would still apply to bullets of similar construction under which the rule of thumb was originally derived.

However MonoMetal bullets tend to be longer than jacketed constructed bullets of similar length. There are also many who have observed these bullets out penetrating equivalent weight jacketed projectiles.

Could it be, length really is important?

I think the old rule of thumb >.305 SD for solids still applys. It is not so clear for soft points as bullet construction makes a big difference. A bullet such as the fail safe with a SD od .260 will probably penetrate more then a conventional soft point with a SD of.305 all other things such as caliber being equal.

465H&H

The Barnes X is more like a solid than a soft. SD still applies for solids. It also applies to softs, but of course it is dependent upon construction. Heavy bullets (high SD) are the only way to fly.

Obviously the advent of the monolithics has changed the course of our thinking in regards to Sectional Density, its a whole nuther ballgame now...and even with solids IMO..A 350 gr. flat nose monolithic solid is certainly the full equivelent of a 400 gr. conventional solid, in a 40 caliber rifle, according to every test I have run and every test I have read about...They are the same length for all practical purposes and the monometal bullet is considerably harder and less plyable..It will penitrate, in most cases, more than a conventional solid.

I have no scientific bases for my opinnion, but I do have a lot of experience with the use of both on big animals and thats what I base this post on...and the bottom line is what works, not speculation...

Ray,

You're probably right. If flat nose bullets give better penetration, and straight line penetration, then bullet weight and SD may take a secondary role in many cases.

one of my thoughts concerning barnes x bullets is the cutting effect they must have. A lead cored bullet mushrooms out fairly flat with a soft metal leading edge. a x bullet mushrooms out with those copper petals leading the way. The edges on the petals are sharp & with the bullet spinning away madly it makes me think that they litteraly cut and chop their way through rather than just pushing through. It's my belilef that this cutting action not only acts kind of like a broadhead on an arrow, but yields greater penetration as well by cutting instead of pushing.

I think it is a balance of SD and velocity.

An SD of 305 at an impact velocity of 225fps is adequate. Push the velocity up and you can lower the SD. Drop the velocity and you need a heavier bullet. ie an SD of .320 for an impact velocity of 2100fps works just fine as well.

Mono's bullet shape etc have a limmited effect on penetration unless they fail and distort which will significantly reduce penetration.

Could it be possible that the length of a bullet has some bearing on penetration? Obviously the greater the SD the greater the length when an identical material and bullet form is used. But, if copper Barnes bullets have a similar length at a given weight as a heavier lead bullet, might this not have an effect on penetration?

More information to help clarify 'sectional density'

SD

I love Barnes X bullets but they don't "cut and chop" their way through animals. I have never seen evidence that bullets I shot "bored" through animals. The rotational energy of the bullet is insufficient to overcome bone and tissue. I do believe that the sharp petals damage more tissue than ordinary bullet mushrooms.

While I think GS Custom bullets, the article by Mr. Schultz referenced two posts above is a perfect example of writing paper to justify something you wish to prove. He has a very, very good product (when you can get it), but when he says that regardless of SD, as long as velocity and weight are sufficient to penetrate, everything is fine... again, Sectional density being unimportant...

But isn't weight a component of Sectional Density and momentum.. and thus, retained velocity and therefore, penetration.

The real question he avoids is this, I think:
All other things being equal, i.e., original diameter, expansion rate, original velocity, original material and original ogive or meplat shape, with weight being therefore a function length of the bullet, will the bullet with the higher sectional density always penetrate further?

Put it this way... GS flat nose solids in .375 caliber. Will the 300 grain bullet at 2500 fps and a SD of .305 always out penetrate the 270 grain version at a SD of .272, assuming the velocity of the lighter is calculated to have the same original momentum as the 300 grainer at impact? I think, no.

And is my premise correct because the lighter (less SD bullet) will necesssarily have a higher original impact speed, and friction, having a geometric curve, therefore slow the lighter's momentum quicker during its quicker decelleration?

Heck, I haven't even had a drink tonight and I'm waxing idiocy... Can you tell I didn't take physics in college and only made an "A" in high school because I know what brand whiskey the teacher liked?

An interesting "variation" on the sectional density issue concerns the so-called bore rifles.
A couple issues ago of Double Gun Journal contained an article by Sherman Bell in which an eight bore H&H was taken to Africa and used on both elephant and buffalo. Penetration on the buffalo was almost complete front to back, while the elephants head was completely penetrated. If you calculate the sectional density of the round hardened lead ball used, you get about .110.
somewhat less than .300. So, somewhere between
maybe .510 and .900 the sectional density concept appears to break down.

quote:

Originally posted by JudgeG:

But isn't weight a component of Sectional Density and momentum.. and thus, retained velocity and therefore, penetration.
Put it this way... GS flat nose solids in .375 caliber. Will the 300 grain bullet at 2500 fps and a SD of .305 always out penetrate the 270 grain version at a SD of .272, assuming the velocity of the lighter is calculated to have the same original momentum as the 300 grainer at impact? I think, no.

Right, but esp. with a greater difference in weight, you can´t compensate mass by velocity without getting too high pressures.

quote:

And is my premise correct because the lighter (less SD bullet) will necesssarily have a higher original impact speed, and friction, having a geometric curve, therefore slow the lighter's momentum quicker during its quicker decelleration?

That is a very strong argument to use bullets with a high SD for penetration.

quote:

Originally posted by 577ne:
A couple issues ago of Double Gun Journal contained an article by Sherman Bell in which an eight bore H&H was taken to Africa and used on both elephant and buffalo. Penetration on the buffalo was almost complete front to back, while the elephants head was completely penetrated. If you calculate the sectional density of the round hardened lead ball used, you get about .110.
somewhat less than .300. So, somewhere between
maybe .510 and .900 the sectional density concept appears to break down.

I don´t believe in such a story. No exact description of the conditions.
There are many reports from the older days on failure of the big bores with respect to penetration.
The ivory hunters always used lung/heart shots with varying succes. In emergency (charges) they sometimes had luck with side head shots, but with frontal head shots it was impossible to bring down an ele.

JudgeG,
You are spot on, even when sober. The RIP Steel Maiden is designed to address this very question.

My gut feeling is that there is something optimum about a bullet of .300 SD for penetration, and a velocity up to 2700 fps before diminishing returns due to increased drag/media resistance are important.

Sectional density much over 0.300 is silly, especially with monometal Flat Nosed solids.

Hi 577. Any danger of posting that article? The early hunters here tried 2 bore (Baker) 4 bore (selous) 6 bore (Cummings) and 8 bore (most). None would reach an elephants brain from the front and selous rated the .303 above the 4 bore as a safe weapon for carry against elephant (different story against buff or Rhino). I guided one hunt where the client used a 4 bore breech loading (cartridge) smooth bore elephant gun dating from the 1880's. He used both round and conicals and even though the bullets were hardened with pewter or hot quenched in water, they were not particularly impressive on an elephants head. (he shot his bull in the shoulder anchoring it, and tried six shots to drop it with a brain shot and ended up heart shooting it).

When we were doing the trials in the early 1990's to get black powder hunting re-legalised in Zim we conducted fairly extensive trials with 8 bore rifles. That is a buffalo thumping round of note, and they are very lethal on heart and even side brain on elephant but we never got one down with a frontal.

quote:

Originally posted by Norbert:

quote:

Originally posted by 577ne:
A couple issues ago of Double Gun Journal contained an article by Sherman Bell in which an eight bore H&H was taken to Africa and used on both elephant and buffalo. Penetration on the buffalo was almost complete front to back, while the elephants head was completely penetrated. If you calculate the sectional density of the round hardened lead ball used, you get about .110.
somewhat less than .300. So, somewhere between
maybe .510 and .900 the sectional density concept appears to break down.

I don´t believe in such a story. No exact description of the conditions.
There are many reports from the older days on failure of the big bores with respect to penetration.
The ivory hunters always used lung/heart shots with varying succes. In emergency (charges) they sometimes had luck with side head shots, but with frontal head shots it was impossible to bring down an ele.

This is probably just a case of gunwriter typewriter. Authors should realize that someone might actually follow their example and get hurt!

Ganyana: The Double Gun Journal is copyrighted, so its a federal offence to reproduce that article. It appeared in the winter 2003 issue.
In fact, the hunter confirmed exactly what you
describe: a thumper on buff, deadly on heart and
side brain ele shots. The hunter described in
DGJ only shot the ele from the front when already
dead, and got 31 inches penetration. So, he
confirms your findings on buff, and ele heart/
side brain shots. The article is authoratative,
and even speaks to the "doubting Thomases"
I would recommend people read this article,
and consider Ganyana's observations before
being too dogmatic.