A 9 year old girl took a bear that big? Pretty impressive. But that's kinda more proof they are t bullet proof.
No 45ACP isn't a front line weapon. But it can be used if necessary or as a back-up. Either way it's been around for a very very long time and has obviously taken numerous bears too. Just as .22's have. Doesn't meant its the 1st line defense. But to those saying 45ACP is just gona **** the bear off - you're wrong. If that was true then how have people taken down bears with 45ACP? Or dropped them with the low .22 in one shot? Now if your going against a HUGE bear in say Alaska, a 45ACP is risky. Can it work? Of course. Would I use it as first line? Heck no! But nearly any caliber can take out a bear. So if a .22 has taken numerous bears, I'm sure the more powerful 45ACP can too. Again, it's not the best FRONT LINE/1st choice but it can and has worked before.
Heck I read a story where a man used a can of axe deodorant and lighter on a bear and got it in the face! Needless to say the bear ran off stumbling into things and hitting things since it just got blasted in the face with fire. But that was a can of axe spray and a lighter that stopped a bear. I'd feel much safer with a 45ACP than a can of hairspray and lighter.