Great stuff to talk about after dinner at the campfire. What your skill level is, the game you are hunting, the distances you expect to see and shoot at game play a part in what cartridge and bullet you use to hunt with and kill game.
It has been my experience and those of millions of veteran hunters that accurate bullet placement is the beginning discussion of stopping power. Accordingly, without good bullet placement in a vital area the discussion simply evaporates into the smoke rising from the campfire. First things first, shoot accurately!
Having said that it is important to understand the elements of Terminal Ballistics when discussing big game such as large northern whitetail deer, bear, bison,and moose. If a bullet has sufficient energy to damage vital organs it will kill cleanly, some cartridges do this better than others. I believe it is better to err on a moderately larger rifle cartridge if you can shoot it accurately especially if you are a hand-loader.
Cartridges that are adequate in stopping power for deer abound. I believe the 6 mm/ .243 is an excellent starting place as long as bullet construction and weight are designed for deer where the shot is broadside and distances are known. Clean kills for this caliber are well documented to 300 yards with a 90 to 105 grain bullet and recoil is very low. Those who are veterans and can handle recoil better may prefer a cartridge that has more power/kinetic energy and bullet weight such as the .308 Winchester, 7mm08, .270 Winchester, and the 30-06 Springfield. Most of these do well in the 120 grain to 180 grain weights. Jack O’Connor created worldwide fame of the .270 Winchester with a 130 grain bullet because it had moderate recoil and packed tremendous downrange energy but Jack hunted mostly out west where trees and branches were not in the way. Still the .270 Winchester and the 30-06 corner the market for most adult hunters. Those of us that hunt in brushy areas may want a heavier bullet that deflects less in brush such as the 35 Remington,444 Marlin or .375 Winchester for quick examples. The .338-06 and .338 Marlin are great for hunting game in brush too but can reach out when needed. Of Course if you hand-load you can make some big bore rifles shoot slower or faster as there are loads and bullet combo’s that can achieve this, like my .375 Ruger which replicates the .375 Winchester and the old 38-55 Winchester when hand loaded for deer and bear. At full power the .375 Ruger shines for Bison and Moose. There are time when hunters may want more stopping power for the game they are hunting because either the game is potentially dangerous at close quarters or of such size that they want to anchor the animal right there or both. I anchored this 800 lb small Bison with one shot from my M77 Hawkeye African in .375 Ruger with a single 260 grain Nosler AccuBond traveling at 2600 fps.
The bullet entered the last rib and drove forward through the chest cavity wrecking the heart and lungs and exited the far shoulder. The bull collapsed in just a few steps. Stopping Power is a nice ally in that situation as there was ample hydro-static shock and penetration.
Where “stopping power” by definition seems to have derived its roots is the effect of “hydro-static shock” effect on blood and tissue, so fast and severe that it can rupture tissue far away. It is not just speed of the projectile that produces the effect of “Stopping the animal in its tracks” it is a combination of speed and penetration that does it. Penetration has a lot to do with bullet speed and weight, its cross sectional area, shape and momentum.
A bullet that travels faster than the speed of sound for example carries with it a bow wave as it travels.
Bow shock wave image from Wikipedia: http://en.wikipedia.org/wiki/Bullet_bow_shockwave
I believe that this wave may be responsible to a large degree for hydro-static shock that can damage tissue and organs not near the wound channel. In some cases via hydraulic effects in arteries this wave can induce shock as far away as the brain especially if speed is sufficient with penetration. The shock wave in general disrupts tissue to such a degree as to turn it to a jelly like mass. The liver can be an organ that is inedible if it encounters hydro-static shock as it has happened to me.
The cross sectional area and shape of the bullet face and bullet weight known as Sectional Density (SD) contribute to penetration and momentum that continue to provide damage to vital organs
“Sectional density is the ratio of an object’s mass to its cross-sectional area. It conveys how well an object’s mass is distributed (by its shape) to overcome resistance. For illustration, a needle can penetrate a target medium with less force than a coin of the same mass.
Sectional density is often used in gun ballistics where sectional density is the ratio of a projectile weight, to its diameter. Sectional density is important to understand when selecting a cartridge bullet combo.”
Here is more on its value from Chuck Hawkes http://www.chuckhawks.com/sd.htm
To find the SD of your rifle bullets: http://www.beartoothbullets.com/rescources/calculators/php/density.htm?
I found the SD for the 90 grain .243’s I am testing to be very adequate for deer.
Further there is discussion of the Controlled eXpansion (CXP) Performance Rating System developed by Winchester is here. http://www.chuckhawks.com/cxp.htm
Bullet Construction can be Lead, Copper sheathed spitzer and round nose, Partition/A-frame, solid gilding metal that can flare like the Barnes and Nosler E-Tips. Note: a round nose bullet or flat point must use more energy up front to enter the skin and tissue and provide more of this shock wave value at entry.
As an example all Dangerous Game bullets are round nosed or flat-point of sufficient SD and mass that it is like getting hit with a fast moving barn door instead of a knife blade.
Further that if we assume that a higher SD bullet that grows in diameter (mushrooms) as it penetrates tissue, providing a larger wound channel.
If you skipped the Chuck Hawkes articles go back and read them. There is a lot of Campfire Fodder there. Good Hunting!©