That's fine you don't feel safe carrying a 45ACP. Multiple others have said the opposite. This is all personal opinion there is NO FACTUAL ANSWER TO THE OP'S QUESTION. But Saying anything can kill a bear is just a little ridiciouls. You claimed I said "anything" could take out a bear. Where did I say that? I never did. The quote I quoted did, not me. And he was talking about guns not "anything" like a rock or stick"
The OP's question cannot be fully answered with 100% accuracy. Where is he going? How big of bears? Is he going into an area where there's a 5% chance he'd come across a bear or an area where theres say an 80% chance of coming into a bear. Some feel safe with 45ACP some don't. I simply stated that it *COULD* work since lesser has worked such as a .22.
But I clearly said 5X over that I wouldn't go without a 12 gauge, and the 45ACP (or 44 MAG) would only be a side-arm.
So No, I wouldn't feel comfortable with JUST a 45ACP unless it was small bears But I'd feel 100 times safer with a 45 ACP than nothing at all.
I think this response nailed it but no one is paying attention:
It all depends. I've seen an Alaska black bear dropped with a single head shot from a 22 caliber Single Six. On the other hand I've seen 357 magnums glance off of a similar bear's face.
The moral of the story is that if the shot is well placed almost anything will work. If it isn't well placed it really doesn't matter what you have.
That answer is very correct.