Originally Posted By: Montanero
It is a ratio of velocity and mass, kinetic energy. A small bullet with great velocity can do great damage, but it still needs to hit something vital and do serious damage to it. It is more about bullet placement, marksmanship. Emptying a large caliber handgun at a charging bear may do nothing to stop it, or you may get lucky and 1 bullet may hit a vital spot. If you do not take the time to aim, you are just depending on luck.

All of that said, if you have a large caliber with a very high velocity, it will likely do serious damage no matter where it hits. But it is difficult to carry a 50 caliber machine gun around.

Bullet design can increase the amount of tissue damage caused, and prevent over penetration, though with a bear in the wild over penetration is not a significant concern. If all of the kinetic energy of the bullet is dissipated into the target, that is "stopping power". Most handguns do not possess enough potential kinetic energy to stop a grizzly bear, so you must either scare it away, cause enough pain to discourage an attack, or kill it.
OK...my current choice is to carry spray, and I usually stay out of these bears, guns, and spray discussions. My choice these days is bear spray, and situational awareness. However, for those inclined to carry a firearm in bear country, I will make a couple of comments from an Alaska perspective.

First off, while people have on occaision successfully used smaller caliber handguns (9mm, 45 ACP, etc) for bear defense, the general concensus is still to use the most powerful firearm and load that you can hit with. Likewise, in hunting, people have taken bears with relatively small rifles. However, most opt for a big gun. Years ago, in a hunt, I killed a brown bear with a 338 Win Mag, shooting 250 gr Nosler Partition bullets. That did the job. The 375 H&H Mag is also very popular for bear hunting. Hunting guides occasionally have to go into the pucker brush after a bear wounded by a client. Some guides opt for a 458 Win Mag for that sort of work.

For bear defense, the general consensus is either a big rifle such as above, or a 12 gauge shotgun with slugs. If you choose to carry a handgun, most recommend at least a 44 Mag with a 6 inch barrel.

Regarding ammunition, with big bears, penetration is crucial, and outweighs expansion. The ideal shot for a bear is to hit the shoulder, breaking bones and driving through into the chest cavity. Brown bears have big solid bones. And their thick coat, especially when wet, also impeads the bullet. If you hit the head, note that the bones in bear skulls are very thick, and slope like the front of a tank. Over penetration is never an issue with big bears. Hence for handguns like the 44 Mag, most knowledgable people choose a heavy, hardcast bullet driven as fast as possible. See for example: HSM Bear Ammunition 44 Remington Magnum 305 Grain Lead Wide Flat Nose (just an example, no affiliation).

Bottom line, my personal choice is bear spray. For those inclined to carry a firearm, the best choice is the most powerful gun you can consistently hit with, shooting the most powerful penetrating loads you and the gun can handle.
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