Don't know about the best twist rate, but the 7 Mag is plenty for Moose; you don't even need that big-for-caliber bullet. Moose are not very tough critters, really. They die from lead poisoning pretty easily. I'd say that a 7 Mag is a better Moose gun than it is Elk gun. Elk are a lot more resilient, tougher critters to put down, even though they are a lot smaller. And I'm definately not a 7 Mag fan!