I have shot a 270 Winchester enough to be on its 3rd barrel. I KNOW what they are capable of doing and I LOVE the cartridge.

However when I hunt elk or moose where there are a lot of grizzlies, I carry my 375. I have run into them a several occasions.

So I have to agree with Ripp and Schakleton. The odds are that the 270 would do 99.99% of all jobs you would ever call on it to do. And honestly, it would probably be OK on most shots against a bear if you have the correct bullet and keep your cool
BUT---------------
If you luck runs like mine has a time of two, that 1/10th of a percent chance listed above will usually come up in the 1st 10% of your hunts
My 375 kills elk just fine too and I just like how it makes me feel when I am running into predators that can kill and eat about anything they choose to. Some of the bears around here make most African loins look small. I don’t carry a 375 to be a “big man”.

I carry it because I am a MUCH smaller creature than a large grizzly bear.