I have read that the 30-40 craig has been used succesfully for many years to take a lot of north american big game including deer, bear, elk, and moose. The ballistics (from what I understand) are very close to a .300 savage. I say go for it.
The 30-30 has many elk to it's credit WITH GOOD HITS. the 30-40 beats it by 200fps and pointy bullets, too. Just gotta get closer than an '06 that's all.
What a great rifle. What a joy to own and shoot.