There is no documented account of .45 acp ever failing to stop a bear attack (of any kind).
.45 ACP is 7 for 7 in actual use.
Federal .45 hydrshok deep is probably a really good all around choice for defense with a .45 acp. though honestly 230gr ball or any type of flat nose round would also probably work just as well.
https://www.federalpremium.com/handg...1-P45HSD1.html
Statisitcs of handguns vs actual documented bear attacks, as well as detailed accounts of EVERY documented defense vs a bear with a handgun at below link. Handguns of all types and calibers, against bears of all species and sizes, are
96% effective in actual real world cases:
https://www.ammoland.com/2019/08/han...#axzz6IIhseTLw
You can safely carry your .45 ACP with confidence.