I see absolutely no reason why a 7-30 Waters wouldn't stop an elk in its tracks.
What you have to keep in mind is that in many cases bullet contstruction and performance have VASTLY improved over the last 20 years. So it's not just a question of hitting them with something bigger and/or faster. These days if you're using a quality bullet, you're hitting them harder with something better than you would have gotten 20 years ago.
Also the key is to work within your zone of successful shot placement. I have to say good for you to the guys that can honestly shoot a tennis ball sized group at 400, but that ain't me. Just because the gun can shoot that far doesn't mean EVERYONE can shoot it that far.
Know your range and stick to it. The sport is called hunting, not shooting. If you find yourself constantly having to take animals at the very edge of plausable range, you need to ask the question: What am I doing wrong?
Is your setup bad? Do you need to work on your stalking skills, wind management, stealth, tactics, etc? Are you not in condition for the terrain and therefore are not able to move/climb fast enough?
Hunting involves more than just a big gun. Read Pope's book on archery and in the beginning of the book there is a great part about what a man from the stone age teaches him about how far behind Pope is in terms of hunting skills. The tools don't make the craftsman.
Grouse