Several guides in the NW/NE US swear by and have taken many large blacks and grizzlys with the .41 Mag and Remington 210gr JSP factory load.

QUOTE,
"Wayne Bosowicz carried a .357 Magnum Colt Python for years. Then he encountered a situation in which a charged-up bear came down from a tree and tore into his hounds and soaked up an entire cylinder full of 158-grain bullets in its chest without slowing down. Bosowicz immediately changed over to a Ruger Blackhawk in .41 Magnum, which has never failed to stop a bear.

Bullet selection is probably more important than anything, in fact. A black bear is tough-muscled with thick fur, hide and fat layers. You need a bullet that will penetrate through all that, and most hollowpoints used for .41-, .44- and .45-caliber commercial cartridges and handloads aren't good choices. Bosowicz uses commercial Remington 210-grain JSP softnose loads in his .41 Magnum, and recommends any similarly structured loads. In .44 Magnum a 240-grain JSP, or a 220-grain (or heavier) silhouette-style bullet like Federal loads commercially, or Sierra and other bullet-makers offer as components, would be a good choice."