> You'll often see guys carrying 44 magnums in grizzly country, but the evidence seems to suggest that common 9mm rounds are effective enough. Even the lowly 22 rimfire is represented in the data with success against black bears (but not polar bears). I don't know anyone who would recommend 22 rimfire for deer let alone bears.

> Given this, I think it's reasonable to select the venerable 7.62x39. This is a common chambering for semi-automatic and even automatic rifles with high-capacity magazines, which would obviate the need to load each bullet individually. It also is easy to obtain armor-piercing rounds in this caliber if penetration is your concern. This is still a punishing round to fire a lot of, but with a modern recoil management system it's manageable.

So, the .308 is extremely common in the US and is somewhat similar to the 7.62x39. A .308 fires a typical round with, oh about 2500 ft-lbs of muzzle energy. Meanwhile a 44mag has maybe 1000 ft-lbs of muzzle energy. An Ak-47 is also 7.62x39 and has ~ 1500 ft-lbs of energy. That's a hell of a lot more grunt than a 44 magnum, any way you dice it.

At that point, skip the armor-piercing or FMJ and go hollow point. There's more than enough power in that round and the larger wound channel is probably a plus.