Redhawk1
I agree with Lawdog, the handgun is only good if that's all you have. If you have a rifle like a three-sixbits why on earth reach for a handgun? The 10 rounds of 300 grainers will make you sleep better in Alaskan bear country as Lawdog says.
As for caribou hunting in Alaska and going nose to nose with brear grizz, been there - done that - got the teeshirt. I've hunted the Mulchatna herd north of the Nushigak up 15 Mile Creek. (I know I am butchering the names but don't have my maps here for proper spelling) The average caribou is about twice the size of any whitetail I've ever seen but standard cartridges will kill them quite nicely. I suggest a quality bullet, heavy for caliber though as their hair/hides are pretty thick and they are pretty solid in the front end. Shoot them low through the shoulders (heart/lung shot) if you can. Don't shoot them "behind the shoulder" unless you like a gut shot mess as their paunch extends farther forward than deer or elks.
When they are migrating (in September that is a good bet) all they do is eat, sh*t and move. No sense trying to chase after one, no matter how good the trophy is, as you won't catch it and it won't know you tried. Again they just eat, sh*t and move and quite quickly at that! Best to get on some high ground and observe (quality binos or spotting scope is a must if looking for a trophy) the herd that is still coming at you. When you spot the one you want, get out in front and ambush it. Ranges will usually be 50 to 100 yards. The nicer bulls will either be in small groups by themselves or bringing up the rear in larger herds 10 to 100+) led by an old cow. Where she goes so will go the rest of that small herd. If you are really in the path of migration you can see numerous herds in all directions (Probably several thousand if you have a good vantage point).
When I go to Alaska again to hunt caribou (I will) the rifle I will take is my three-sixbits which is a M70. I will have probably take some cast bullet loads (377449/275 gr at 2200 fps) for the caribou, some .375 gr RBs over 4 gr of BE at 890 fps for Ptarmigan and some 285 gr Speer Grand Slams over 72 gr of Varget for 2675 fps so I can sleep at night or concentrate on the wonderful fishing the Nushigak has to offer. Last trip I took a 30-06 loaded with Hornady 180 SPBTs. While it did well killing two very nice caribou it was looking very small when I was at 25 yards nose to nose with that grizz. The three-sixbits may be "over kill" for the 'bou but so what?
Larry Gibson