You might consider a larger caliber for bears.
I like the ones that start with “4.”
Tim Sundles, who owns Buffalo Bore, really likes .45 and larger caliber bullets.
https://m.youtube.com/watch?v=nAsj1JZwGbU&pp=ygUUYnVmZmFsbyBib3JlIDQ1IGNvbHQ%3D&ra=m
Everyone Knows 9mm
Is Just a .38 short,
Grab Some Bear Spray too!
.
I’m hoping Yellowstone
Goes Big Time as We
All need the Distraction!
.
TEOTWAWKI +
I feel fine.
I carry .357 with Buffalo Bore for Griz every time. That’ll drill a 4.5 foot hole through any part of Griz, and I’m a good shot under pressure.
As Dean Weingarten (“MarkTwain” here on FR) documents, most any caliber will work to deter Mr. Bear. I’m confident that 9mm Buffalo Bore will go at least 3 feet through black bear, and break off their attack.
If it weren’t for Rich (DainBrammaged, Resquiat In Pace) passing his guns to me before he passed, I’d get a .44 Magnum. But Rich had a sweet Ruger Blackhawk Flattop that’ll work just fine. Story here:
https://www.ammoland.com/2025/06/american-gun-culture-be-rich-be-frank/
Grok on calibers:
The .357 Magnum is generally more powerful and better suited for bear defense than the .45 ACP. 
Ballistics Comparison
• Energy: .357 Magnum typically delivers higher muzzle energy (often 500–900+ ft-lbs depending on load and barrel length) compared to standard .45 ACP (around 350–500 ft-lbs, with some +P loads pushing higher but rarely matching hot .357 loads). 
• Velocity and Penetration: The .357 is a high-velocity cartridge (often 1,200–1,500+ fps), offering flatter trajectory and deeper penetration — critical for reaching vital organs through thick bear hide, muscle, fat, and bone. The .45 ACP is a slower, heavier subsonic round (800–1,000+ fps) that excels in creating large wound channels in softer tissue but often lacks the penetration needed for large, aggressive animals. 
• Bullet Selection: For bears, hard-cast or heavy flat-nose bullets are preferred in both for maximum penetration. The .357 has strong options in this category (e.g., 180–200 grain hard-cast loads). The .45 ACP has fewer dedicated hard-cast bear loads and generally underperforms in deep penetration tests against large game. 
For Bear Defense Specifically
• .357 Magnum: Considered adequate (or the bare minimum) for black bears and marginal for larger brown/grizzly bears with proper hard-cast ammo and good shot placement. It has documented successes in bear encounters and is praised for its penetration and “bear medicine” potential in revolvers. Many experts and users prefer it over .45 ACP for woods defense against four-legged threats. 
• .45 ACP: Capable against smaller threats or black bears in a pinch but widely viewed as less effective due to lower energy, velocity, and penetration. It is better suited for human self-defense (larger permanent wound cavity) than stopping charging large animals. 
Key Caveats:
• Handguns are a last resort for bear defense — long guns (rifles/shotguns with slugs) are far superior.
• Shot placement, ammo choice (hard-cast penetrators), and shooter skill matter more than caliber alone. Bears have thick skulls; brain or spine shots are ideal but difficult under stress.
• Neither is ideal for large grizzlies; .44 Magnum, 10mm (with hard-cast), or larger are more commonly recommended as step-ups. 
In summary, choose the .357 Magnum (revolver with hot hard-cast loads) over .45 ACP for bear defense. Always prioritize avoidance, bear spray, and proper training.