My 4 inch (not 4.25 inch) 45LC Redhawk will shoot a 345 grain Beartooth bullet at 1235 fps with a heavy load of H-110.
This is really about as heavy a load as I'd want to carry for bear defense. In the article I mentioned above, the bear apparently had the guys' arm and hand in it's mouth and the guy pulled his 44M with his free hand and shot the bear 3 times. The heavy magnum loads are hard to shoot with one hand.
Here's a news report about the bear attack
http://www.ktuu.com/news/news/sow-shot-dead-after-attacking-eagle-river-man/27137910