10mm Caliber Pistols & Their Defensive Use Against Bear Attacks: Known Incidents

Grizzly bear downed at 10 feet by Jimmy Cox with a 10mm pistol

U.S.A.-(AmmoLand.com)- – The 10mm pistol caliber is gaining supporters as a suitable pistol caliber for defense against bears.

The caliber has long been known as an excellent pistol hunting cartridge. In this correspondent’s study of the use of pistols in defense, eight cases have been discovered where 10 mm pistols were used to defend against bear attacks. Six of those cases were with the 10 mm only. One case was in combination with a .340 Weatherby magnum rifle, and one case was in combination with a .45 ACP pistol.

The cases are shown in chronological order.

1. August 18, 2002, Western Talkeetna Mountains, Alaska, 10mm grizzly bear. The information comes from a personal interview with Jake Jefferson.

A problem bear was becoming much too familiar with people and property at the lodge on a lake. Several cabins had been broken into and ransacked for food on the other side of the lake.
Professional guide Jake Jefferson had his 10mm pistol. It had been built by his brother on a six inch longside 1911 frame, with an eight shot magazine.
Jack attempted to haze the bear away from the lodge.  He fired six shots near the bear, which indifferently moved a little way away. It came back quickly and tore up a bunch of empty coolers.  The bear moved out of his sight.
Jake looked for another firearm, but did not find any close to hand.
Jake heard “hey bear” from the other side of the lodge.
As he came around the corner, the grizzly was quartering toward him at 10-15 yards. He only had two shots left. He fired one into the back pair of ribs, which later was found to have missed the chest cavity, and traveled through the abdominal cavity to the inside of the hide on the other side.
The bear immediately ran off. It was nearly 11 p.m. with a fair amount of light, but getting darker. Jake decided to wait for morning to track the bear.
Next morning, Jake found a very sick bear on top of a beaver food pile, in the lake, with only its head above water.  Jake used a rifle to finish off the bear. The boar squared at 7 1/2 feet.
Jake had a hunting tag for the bear. In Alaska, it was officially listed as a hunting kill, not a defense of life and property.

2. September 10, 2015, Pass Creek Grizzly .340 Weatherby Mag and 10mm   30 miles SW of Cody, Wyoming, Freedom of Information Act (FOIA) reply to AmmoLand, Page 310

Bear had taken a sheep carcass. It charged the guide and hunter from about 10 yds. At 7 yards it was shot with the .340 magnum, then twice more. The hunter shot at the bear four times with the 10 mm Glock. The charge was stopped and the bear rolled down the slope.

Investigators found pistol brass and bear carcass, which was consistent with the hunters statements.

3. May 16, 2016, 10mm  Black Mountain in Wyoming East Fork WHMA Grizzly FOIA page 426.

On May 16, 2016, a man was looking for shed antlers on Black Mountain in the Wyoming East Fork Wildlife Habitat Management Area. A sow grizzly with two cubs of the year charged him. He fired several warning shots at the sows feet, but the bear kept coming. He shot seven or eight times, and emptied  his pistol, as the bear rolled past him and hit a tree. He left the area. The grizzly bear was never found. Rain had washed away the evidence. No blood or hair found.

4. 29 July 2016, Alaska: Kim Woodman Kills Charging Grizzly with 10 mm

On 29 July, 2016, about 4 p.m. Kim Woodman was attacked by a sow brown bear at Humpy Creek.

Kim had a Glock model 20 10 mm pistol with him. He was able to stop the attack by shooting the bear as it charged at him. While backing away from the charging bear, Kim tripped and fell backward. He instinctively attempted to fend off the bear with his foot, while he concentrated on firing the shots that saved his life. The last shot was just short of contact. It probably hit the bear in the chest, but also took off the tip of one of Kim’s toes.

5. 25 July, 2018, New Mexico: Man stops New Mexico bear attack with 10mm Glock 20

Bridger Petrini was attacked by a near 400 lb cinnamon black bear. He kills the bear with his Glock 20 10mm during an extended fight. This correspondent interviewed Bridger. He fired about 7 or 8 shots from his Glock model 20, while the bear attacked him, clearing one malfunction during the battle, as he and bear rolled down a steep slope. He spent considerable time in the hospital, but he survived.  The case is detailed at the link.

6. 18 September, 2018 Alaska, 10mm Grizzly Bear Defense on Archery Moose Hunt, Anthony Reyna Relates story, “Jimmy” is the shooter.

At this point we haven’t spotted the moose yet but has seen the crows kick up, and less then a second after that you hear the roar, from our 12 o clock, and boom freaking 7 1/2 foot brown bear yards 10 yds away and full charge, my buddy Jimmy who was leading yells ever so calmly “Oh fuck bear” draws his Glock 20 and without hesitation drives two bullets into the charging boar at roughly 10 feet from him. One to the head, one to the chest “Perfect.” At this point, and it being so fast it’s hard to comprehend what had just happened.

7. 23 September, 2021, Island Park Idaho, Grizzly Bear 10 mm

Then, on 23 September, a sow grizzly, reportedly with cubs in the area, was shot and killed when it attacked archery hunters near Island Park. The hunters deployed both bear spray and a pistol. The incident is still under investigation, but it appears the bear was shot at very close range. It is elk archery season in Idaho. A source inside the investigation informed this correspondent the pistol was a 10mm.  From idaho.gov:

On Thursday, Sept. 23, 2021, Idaho Fish and Game received a report of a sow grizzly bear that charged two elk hunters in the Stamp Meadows area near Island Park. As the bear charged, one of the hunters deployed bear spray while the other discharged a firearm at close range, mortally wounding the bear. Neither hunter appeared to be injured during the encounter.

8. 10mm and .45 ACP pistol September 27, 2021, Grizzly Bear Wyoming Two Oceans Pass. Interview with Tyler, published on AmmoLand. Tyler was using a 10mm Glock 20 with Buffalo Bore cartridges. The son was using a .45 ACP with hollowpoint bullets.

Tyler remembers he and the son shot, and shot, and shot. The pair fired a total of 31 shots.  Numerous hours at the range paid off for the son. He finished one magazine and completed a speed reload while Tyler was still shooting.

There are a few cases where a person being attacked by a bear is able to reload. This is the first one I have encountered where the reload was accomplished while the bear was charging.

As the bear got within 10 feet, its speed had slowed considerably.  Tyler was concentrating on chest shots. Tyler believes he broke one or both shoulders. The bear veered hard right into a tree. Tyler took a step forward and shot the bear in the side of the skull, through the brain, twice.  The Buffalo Bore bullets penetrated through the brain and lodged in the skull on the other side. The distance was five feet. The deadly fight was over.

Pistols are an effective tool to use in defense against bear attacks. The 10 mm is a good choice. It is a powerful round. 10mm pistols are available with magazine capacities of up to 15 rounds. Several manufacturers make 10mm cartridges with deep penetrating bullets designed for hunting large game or defending against bears. The latest update on this correspondent’s research shows pistols are an effective defensive tool 97% of the time they are used against bears.

About Dean Weingarten:

Dean Weingarten has been a peace officer, a military officer, was on the University of Wisconsin Pistol Team for four years, and was first certified to teach firearms safety in 1973. He taught the Arizona concealed carry course for fifteen years until the goal of Constitutional Carry was attained. He has degrees in meteorology and mining engineering, and retired from the Department of Defense after a 30 year career in Army Research, Development, Testing, and Evaluation.

Dean Weingarten

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Having used and carried revolvers for more then 50 years and well over a hundred thousand rounds through them

It is a myth that they don’t fail.

With a enough grime in them blood hair dirt ect. The cylinder can easily fail to rotate thus experiencing a “failure to feed”.

I carry both types on a regular basis.

With proper mainitance they are both reliable self defense arms.

But stuff happens.

Carry away and carry what you want.


I love semi auto pistols but would not want to have to clear a fail to feed while a bear was chewing on my ass . I will stick with my Ruger Blackhawk. 44 mag or my Tauras Ragingbull 454 C. They never will have a fail to feed problem !


The 10mm has proven to be a effective performer.

But so has others.

Having shot several bears with handguns.

I prefer heavy for caliber bullets with a muzzle velocity of at least a 1000fps.

My 41 210gr and 44 315 mag have worked well.


My parent’s ranch is just a couple of miles from where #5 happened and they are good friends with the young man who was attacked. His incident is the reason I bought a .460S&W and carry it whenever I’m there. I can’t imagine being attacked by a bear, much less having the bear’s jaws locked on me and having to cut its head off to get free.

Deplorable Bill

Good, reliable guns, good bullet choice and good shot placement will save your life. A good 10 mm is close to a 41 mag. in power but not quite. Some loads are about 44 special in power. Choose the right load. Using fmj or swc or sp bullets will get penetration needed to kill a bear. Whatever you do do not use hp ammo, while this is the medicine for two legged predators they may not go deep enough to stop a bear from killing you before it also dies. As with everything else in defense with firearms, bullet placement… Read more »


Hoped you recovered the car hit bear.

They are very good eating.

Henry Bowman

ROFL!! Good eating??? Yeah right. I called the Dept. of Natural Resources, told them the exact location which was 1/2 mile past Hwy 230 headed East. Where I am you do not need to wait for a ranger to show up, this stae is big and rangers are few. It takes a while to get where they’re going. I like bears, and my fiancee even more so. We were upset. Some people like Yogi Bear, some like Smokey the Bear and the whole “Only you can prevent forest fires”. I loved Smokey as a kid. But in these times, many… Read more »


or make some bear grease

Henry Bowman

I’ve been eyeballing 10MM’s for a while and though I have my wishlist narrowed down to a few options, I’ve been looking and waiting for a really good deal. I just moved to bear country and I’m close enough to spit over the border from my back 40. So yeah, lots of bears. Last fall my fiancee and I were headed to town when a black bear yearling came barreling out of nowhere (the stretch of highway we were on was just a few yards from shoulder to treeline) – BAM, hit the poor thing and it went flying off… Read more »

Matt in Oklahoma

The 200-220gr hardcast at 1200fps seem to be the ticket though other options like the Extreme Penetrators do well too. I’m a fan of Underwood but the hardcast wasn’t accurate in my G40 so I went with Steinel. Buffalo Bore makes some good loads too. Avoid the high speed hollow points for bear because of lack of penetration. Your better off with ball ammo. I’m much faster with a 10 than other heavy calibers like 44, 454, 500 etc. and 16 over 6 is a good thing too. I hope no one ever has to but I wish ya the… Read more »


I can tell from personal, hollow points are a no ,


HP v FMJ, I choose to hedge my bets. My mags are loaded alternately with HP and FMJ, with a double-tap intent.


-45 Super is basically the equivalent of the 10mm in power. A .45 1911 can be converted so that it will run .45,.45 +p and .45 smAuoer, all with one gun, depending on wrangle, personal defense, hunting and bear defense!