Again My standard answer. Whatever You have in the gun when You need to use it.
Now the Marines that frequent our forums will love that comment, the sailors not so much.
Just remember "if it is worth shooting once, it is worth shooting several times!"
In October 2010 a man released his privet zoo then killed himself. A responding Muskingum County deputy kill the Grizzly with his issue Glock in 40 S&W. For the Michigan camp bears, your EDC ammo should be just fine! The BB monster killers may have "Overkill" problems. There is such a thing as "Too much of a good thing!"
Ivan
It seems like the Marines favored the 1911. If you look at pictures of Naval aviators in the Pacific, you can see that most Marine pilots carried a .45 Auto, while the Navy pilots carried Victory Models.
"Rules of Gunfighting According To The USMC".
Rule Number Six: Do Not Attend A Gunfight With a Handgun Whose Caliber Does Not Start With A "4".
Some of my favorites
1. Bring a gun. Preferably, bring at least two guns. Bring all of your friends who have guns.
7. In ten years nobody will remember the details of caliber, stance, or tactics. They will only remember who lived.
11. Always cheat; always win. The only unfair fight is the one you lose.
12. Have a plan.
13. Have a back-up plan, because the first one won’t work.
I have seen it in various forms and orders, and with an addition here and there, but I will always try to adhere to the principals