JP: It is safe to assume that hundred of thousands (if not more) of Elk have fallen to the venerable 30-06. Hunt hard, get close, and hit 'im in that big 'ol boiler room. One word of caution: Elk have large and extremely strong shoulder blades. They are located above and quarter behind, the front "elbows". A shot there could severely damage the animal without killing it, and it might be capable of running a great distance. Elk are awesomely powerful animals, and much more than big deer. Perhaps some one on this board could direct you to a drawing or photo of an elk with the vital indicated on it. You might also try to locate an archery target that has those areas indicated. Jump on to the Rocky Mountain Elk Foundation site and check out some of the great elk photos they have.
www.elkfoundation.org You can then spend some time visualizing elk in dark timber, Aspen stands, open sage and other habitat, and picture them broadside, quartering towards and away. Which reminds me of another thing to consider: Elk not only have tough shoulder blades, but their ribs are pretty stout as well. Be very careful if an animal is sharply quartered towards or away. It is entirely possible to glance a shot off of an elks' rib cage with out the bullet catching anything more than hair and skin. Have a blast, and prepare for the addiction!