[DarthVader]

A .45ACP is simply not enough fire-power to kill a grizzly. Most .45s have muzzle velocities of 800 - 1100 fps and muzzle energies of 380-500 ft-lbs. You need something much larger and heavier with a muzzle velocities from 1200 - 2000 fps and muzzle energies from 1500-3100 ft-lbs. An ideal sidearm for Grizzly country would be a Ruger Super Red Hawk Alaskan snub nosed revolver chambered in .454 Casull Super Magnum or .480 Ruger.

[DKM]

Both my wife and I carry Ruger Super Red Hawk Alaskans, in the .454 version. Nice thing about them is that they also shoot .45 long colt, for practice it’s an easier load. We are right smack in the middle of Grizzly country in south-central Alaska. Also provides protection against the much bigger threat here.... moose.

[Stonewall Jackson]

That's what I told Ryan. He was looking at a Springfield Armory 1911A1, but I told him to hold off on that until I talked to folks here on FR. From the responses so far, it looks like a double-action .44 magnum or .454 are the most popular recommendations.

I have to stop by work tomorrow, so I'll tell him the top recommendations. Thanks everyone for your suggestions.