The Powder Valley web site states "Alaska and Hawaii freight charges will be reviewed prior to shipping. ...customers will be notified in advance of shipping."
MidwayUSA's web site states powder can only be shipped ground rate within the continental US.
I don't think it's possible to ship powder ground rate to Alaska. I think powder is barged or trucked into Alaska by the wholesalers.
Lived here 42 years and have a relative owned & operated a gun shop here for 37yrs. Never heard of anyone ever shipping gun powder, primers, or ammo up to Alaska. If you drive up, you can haul some powder with you thru Canada. Like a 16 lb maximum limit.