Since I have not had to really make a plan for being in Grizzly country, this thread has become somewhat of an obsession! This will be the 4th time I re read through... every day something comes out that redefines something from the past.
I know I never imagined a 3.5 liter gas motor that could keep up with a 7.3 diesel in terms of towing capacity, but we have that today.
As for bullets... we used to have choices that were the weight of the bullets... 30-06 had 120, 150, 180, and 220 grain bullets... 168 if you shot "match bullets"... now we have dozens in each weight class...
Guess my point is in today's world, to answer the question that started this... absolutely a 45 ACP be used for defense against a bear... is it the best choice... if we went on this, all of us would be reloading for the same rifle caliber to shoot an Elk.
Today's ammunition is so far removed from what it was even just 10 years ago.
Not poking at anyone, but one of my decisions to post again was hearing some say absolutely not for the 45 but a 40 cal is fine... the 40 cal ballistically is an attempt to make full house original 10 mm loads work in smaller guns for smaller hands with controllability that everyone in law enforcement could handle (lot more to this but not going to bore y'all... look into the 10mm or fbi Miami shootout)...
Longer story shortened... 40 S&W barely duplicates 45 ACP ballistics in most cases, but side by side, a 45 ACP can be pushed with a heavier bullet faster.
It's not so much a choice about the caliber but the bullet choice. If you can shoot something like the 255 gr Buffalo bore hard cast in your 45, you pretty much have the same as the 44 mag, 454, 41 mag at the range we are talking about.
I think the problem is people think about hollow points... hollow points for hunting in a handgun are not a good idea in my opinion... hollow points are for helping keep a handgun bullet from over penetrating in an environment that has other people... was very interesting reading about actual use against bears from everything from 9mm to 454... surprisingly the only caliber that actually "failed" was 357... I think it was because the bear was not hit squarely, but anyway.
Additionally... lots of people say that a 12ga slug is the best and that only rifles 338 or larger... well I did some testing today... my 870 ish 30-06 with even just 180 grain partitions was a lot easier to shoot accurately than a Mossberg 509 with slugs. I am sure both would work well if needed... just don't understand the need for a 338.
If... IF... I was going on a hunt specifically for Grizzle I get the 338 recommendation... this post is about the effectiveness of the 45ACP...
Has a documented track record and with the right bullet... maybe even just fmj I wouldn't feel undergunned in terms of it being part of my protection plan in Grizworld. I would want something high cap though.