Many moose have been taken cleanly with the .270, but it requires ideal angle and shot placement..A bigger gun is better and will perform better on the bears also, should the need arise..
I read somewhere that the three most popular chamberings among Alaskan hunters are the 30-06, .300 Win mag and .338...
None of these three is a BAD choice, but if you are deciding between the .300 Winnie and the .338, consider this...Range and recoil are similar between the two, but the .338 will handle a bigger and heavier bullet...
The .338 Win mag with a 250 grain premium bullet is an excellent choice for all around Alaskan hunting INCLUDING the big bears, should you ever decide to shoot one..