Thank you for seeking the truth on an important subject such as defending oneself against a bear attack. BTW, I absolutely love reading stories about bear attacks and bear encounters of all kinds. The most interesting aspects have less to do with the physical damage done by the bear and more to do with the amount of damage the human body can sustain and endure, and the thought process of the victim during the attack and the psychological impact that results, often lasting for many years. The following people used guns on bears but were still unable to prevent contact and subsequent mauling.
The first story is from More Alaska Bear Tales by Larry Kaniut. On pages 168-170 a grizzly mauling victim, Jack Naus, tells his own story in a letter written to the book's author. I will pick up the story where the bear comes in.
"As Dave cried, "It's big, whatever it is!" a medium-sized brown/grizzly bear, weighing three hundred to four hundred pounds, broke through brush and charged from approximately thirty yards away.
"Dave jumped to his right and I to my left, allowing room for the bear to escape. About ten yards into its charge, the bear made a sudden ninety-degree turn toward me. I immediately snapped off a shot--using a .300 Winchester Magnum, 180-grain factory loads--hitting the bear between the head and the left shoulder. He was so close that I saw the dust fly. He bowled over.
"As I fired, I had a feeling my bullet wouldn't stop him, and sure enough, the bear made a forward roll and bounced back onto his feet. Although Dave later told me that I fired in rapid succession, the next few seconds seemed to take place in slow motion. When I reloaded, I thought the round was never going to chamber. My next shot must have hit his skull as I tripped and fell backwards. I still carry lead in my right arm from where the bullet fragmented and ricocheted into my arm. That's how close he was!
"The next thing I knew, I had a large brown bear with his jaws wrapped around my hip. At that point, things got hazy. Dave shouted at me to lay down and take it easy. He shot the bear twice, and the animal false charged Dave and then ran back into the woods.
"I sustained about five half-inch round punture wounds spread below my navel and around my left hip to my buttocks; a five-inch gash on the inner left leg and groin; a gash from the mid-cheek of my face to the top of my ear; and four to six entry wounds on my left arm from my own bullet."
300-400 lbs. is a relatively small grizzly; a .300 Winchester Magnum is a large and powerful weapon. The second story is from the same book, pages 178-183, told by the victim, Ben Moore. Again, I will pick up the story where the bear enters it.
"I came to a wide, open clearing, and I lifted my binoculars to glass for animals. Suddenly, I noticed a bear through the glasses, and my heart skipped a beat. The image was so close it was fuzzy. The bear was on the same ridge where I was standing, about one hundred feet away. At about the same time I put the binoculars down, the bear stood up on his hind legs with his head above the brush. It bobbed its head, opened its mouth and looked at me for severa secons, then dropped out of sight.
"I was a little startled, but not too concerned about being in danger. I've read quite a bit about bears and figured if I didn't react, the bear would move on. I relaxed, standing perfectly still. As I was glancing around, the brush exploded and I saw a ball of fur hurling toward me like it had been shot out of the bushes. I reached down and pulled out my revolver, a .357 Ruger single-action. By the time I drew and cocked my gun, the bear had practically reached the end of the barrel. I pulled the trigger, hitting the bear somewhere in the chest.
"Still the bear charged forward, grabbing me by my lower right leg as he ran by. He picked me up, swung me over his head and actually threw me like I was a feather pillow. I landed on a rock several feet away, barely hitting the ground before the bear was on top of me, chewing my upper right leg.
"Miraculously, I hadn't dropped my revolver and managed to get off another shot; but I was shaking so uncontrollably that I completely missed the bear. I struggled to cock the gun again, fired and hit the animal in the stomach, about a foot from my face. A huge hole opened up in its abdomen and blood poured from the wound, but the injury only angered the bear more. It grabbed me by the head, picked me up and shook. As I heard the bones in my face cracking, the bear dropped me. I fell on my back, staring up at the bear directly over me with its mouth open. The grizzly saw me move and came down for my head again. But as the bear lowered its head, I lifted my right arm, cocked the gun and jammed the pistol clear into its mouth. I pulled the trigger. The timing was perfect. When I fired that final shot, the pistol and my hands were in the bear's mouth.
"The bear shook its head and shuddered. It reared back and took a powerful swing at me with its paw. And, almost as if the bear knew what had caused the hurt, it tried to knock the gun out of the way, but I clasped it tightly with both hands. Then the bear staggered over the ridge and down into the brush."
"My nose was actually hanging off..."
A quick comparison in ballistics:
The energy of a .300 Winchester Magnum at 0 yards is between 3500 and 3800 ft-lb.
The energy of a .357 Magnum at 0 yards is between 400 and 625 ft-lb.
10 mm: 425-649 ft-lb.
.41 Magnum: 600-790 ft-lb.
.44 Magnum: 720-1035 ft-lb.
.45 ACP: 320-540 ft-lb.
.454 Casull: 938-1923 ft-lb.
This post is long enough, but quickly: The energy of a cartridge does make a difference in terms of penetration and damage. If a .300 Win. Mag. is able to glance off of a bear's skull or fragment and ricochet, how can anyone suspect that an inferior (less powerful) cartridge could possibly do any better? Carry the most powerful weapon possible. If someone would like, I could site stories in which bear spray successully repelled a bear.
In the book Arctic Homestead by Norma Cobb and Charles W. Sasser, Norma tells of her husband Les Cobb successfully killing charging grizzly bears with his .44 Magnum revolver on several occasions.