How does caliber (diameter) rank compared to S.D. and bullet weight in determining effectiveness on game?

It seems obvious that as the animal gets bigger, so must the bullet's dimensions. But which dimension is most important?

For debate, how about comparing a 220 gn RN .308 to a 250 gn RN .358, both at 2250 fps. The game is elk/kudu size, say 600 lb. The .358 must hit harder, but the .308 can likely go deeper. Pros and cons?

In general if the bullet construction remains the same then the bullet should increase in size along with the size of the animal.

The best source for information on this topic is Harald's site.
http://www.mindspring.com/~ulfhere/ballistics/wounding.html

Savage, you say "Harald", you know his name? I rather admire the effort he put into that work.

In regards to the question, one point of consideration regarding caliber and SD is that for spheres volume increases by the 3rd power with diameter, frontal area by the 2nd power. Thus within the limitations imposed by practical twist rates, it is easier to increase SD(and BC) with a larger bore. In other words, you can calculate an extremely high SD for a .17 cal and in theory have as much penetration ability, but shooting it is another story. It is why the larger bores fare so well at long range.

The SD of a given bullet has little to do with its ability to penetrate. What becomes germaine at the point of impact is the retained SD, and this is why light, small bore, thinly jacketed bullets fail to do the job even when they carry high energy levels.

The link above should be required reading for all hunters IMO.

If you really bother to study what hunters use on game, you'll see that lots of cartridges are very, very effective at quickly putting down animals ranging in size from smallish deer to Alaskan moose. Caliber is important, and yes, caliber selection should indeed be a proportional proposition depending upon the animals you're hunting, but no one should get so carried away they they ignore shootability. I'd a lot rather see a hunter go after elk, for example, with a .30-06 than he can really shoot rather than with a .340 Weatherby that he's subconsciously afraid of.

Bullet weight counts, sectional density counts, diameter counts--all of it counts to be sure, but bullet construction and bullet placement counts for more than all the rest of it combined, at least up to a point.

Caliber selection isn't that tough, or at least it shouldn't be. For example, I hunt with a .300 Win. Mag. more than anything else, and have for the last ten years. I've used it on everything from Coues deer to moose in N. American, and for everything from dik dik to eland in Africa. I've almost always used premium 180 gr. bullets and haven't seen the need to go heavier or lighter, even though I have gone lighter. I certainly don't need to use a .300 Winchester on deer, but it's nice to be able to pick the same rifle and ammo up for spring bear in May, African plainsgame in August, pronghorn in September, mule deer in October, whitetails and elk in November, and Coues deer in December. It works at all hunting ranges, on all sizes of animals up to 2000 lbs. in weight, and most of the time what I've shot at has dropped on the spot or at most has taken a few steps and keeled over. Bullets usually go clear through or else remain under the hide on the opposite side. An uncomplicated, uncluttered, simple, and effective approach to cartridge selection, and you could do the same thing with any number of other cartridges as well. And you don't need to make things harder by choosing a wildcat of some kind--just stick with a standard factory cartridge and be done with it.

Back in the early 1970s, Remington ran a series of ads that not only served to showcase Remington firearms, but to pass along some really great and practical shooting tips to hunters. Some of the best PR work ever turned out by Big Green, in my opinion. Anyhow, in one of these tip-ads, the theme was that hunters should pick one cartridge, stick with it, and really learn it inside and out. And I think that's incredibly good advice, which I was finally smart enought to actually follow myself 17 years after reading that ad when I decided to pretty-well stick with the .300 Win. Mag. for 95% of my hunting. I've fired thousands of rounds of .300 Win. Mag. ammo in proctice, and I've taken scores and scores of animals with that cartridge. I sight-in with 180s at around 3100 fps. for 250 yards, and I leave it that way for everything.

Again, you can do the same very same thing with the cartridge of your choice and do very, very well for yourself........

AD

asdf,

Difficult question and I'm afraid no simple answer.

SD is related to weight and diameter, since is mearly a ratio in lbs. to the square of it's diameter, in inches.

So, in your example, a 308 220 grain (SD .331), and a 358 250 grain (SD .279) at the same velocity 2250 FPS, one would expect that the 308 would penetrate deeper, but the 358 would tear up more (expand more) tissue.

But, bullet construction does have a say in the matter. Let's use your example above.

If I had a choice between the 220 or 250 grain @ 2250, which would I use? Answer, none of the above. The why is also related to bullet constuction.

Most bullets, unless designed for low velocity expansion, will simply not open up at velocities below 1900 FPS. So in effect you have a solid bullet.

Both the 308-220 gr and 358-258 drop below 1900FPS at less than 150 yds. So in your above choice your quary must be 150 yds or less to get any useful expansion. That is the paradox of using high SD bullets at low veleocites on thin skinned game.

Can you have your cake and eat it too? YES... In other words can you have useful velocity, and deep penetration. Yes again.

The simple answer is premimum bullets. Most folks think of using premimum bullets only in high velocity applications. But the premimums also have a useful application in boosting veleocity by using a lower weight bullet and not giving up penetration.

Let's use your example above:

308 Winchester 220 grain @ 2250
358 Winchester 250 ggrain @ 2250

In the 308 drop the bullet weight to 180 grains and use a Barnes X for example. Now you can have 2600 FPS, and all the penetration you can handle.

In the 358, drop the bullet weight to 200 grains and again use the Barnes X. Again, you get 2600 FPS, and all the penetration one could hope for.

The Barnes X, inspite of fouling problems, really turns the SD formula's on it head. Barnes X's (and others of like constuction), will out penetrate, regular cup and draw bullets, all the premium bondeds, and allows a hunter to boost velocity, and still get great penetration.

What a simple 308 Winchester will do to game, when you use a 130 grain XLC or the regular 140 grain Barnes X at nearly 3100 FPS (in a 24" barel), has to be seen to be believed.

Northfork Bullets is another option, as their bullets will expand down to around 1700 FPS. So you could use a Northfork 200 grain in your 308 or a 225 grain in your 358, both at around 2400 FPS or better. You will get expansion, and deep penetration, not as much as the barnes, but more than enough for most of the applications these bullets are suited for.

As to your question which dimension is most important? Where you put your bullet in the animal, trumps all.

Regards,

Bob

As Allen says bullet placement counts the most.

Unless you are willing to move up at least two calibers in dia and around 100grs of bullet weight at the same vel. You most likely well not see much differants.

A well place bullet of proper weight for the caliber and well made well work. It is much better to place a smaller bullet in the right place then a larger bullet in the wrong place. But that said you can go to exstremes on both ends.

Too light a bullet in the ribs of two big of animal most likely well not do want you want. Too big of bullet in a gun you can not shoot well well not go where you want it to.

Pick what you can shoot and handle well with a proper bullet for the size of game your hunting and go kill it.

I think you answered your own question. Larger diameter bulets of sim. construction are going to hit harder. You may very well get better penetration from the 220gr/06 but the wound channel will be smaller, especially true w/ hard or solid bullets. Bigger holes are better, bigger holes all the way thru are the best.

I personally don't think caliber selection is particularly important. Pick one of the popular ones on the powerful side of what you can shoot easily and go hunting. I come from a family of one-gun hunters and they all seem to bring home the game when they go at it sensibly.