From what I've read and in talking with my buddies who have killed moose, they say that for an animal that size that a moose is not that hard to kill. They just shot them through the lungs and gave the moose time to lie down. Those bones are big, even the rib bones so I think that you would be best served with a heavy for caliber 140-160 premium bonded bullet like the Partition or A-Frame mentioned above. I've used a lot of 140 grain Partitions from my 7mm-08 and 160 grain Partitions from my 7mm RM on deer and elk and never lost an animal, but don't expect a big blood trail from just that back half going out the far side.
