I was wondering why someone decided to revive a 5yr old thread
But since they have, and it seems to be relevant I'll add to the thread.
A lot has changed since 2012, and a lot hasn't. As to the original question, a 7 mag shoots bullets 10 gr heavier and and .007" larger in diameter to about the same speed with a little more recoil. On paper the 7 mag wins, but by a slight margin that most people cannot use. Trajectories are nearly identical and 10 gr of bullet weight and a .007" bigger hole won't make any difference.
The trend today is toward moderate powered short action cartridges and away from anything magnum. The better bullets, optics and rifles were available in 2012, but were just beginning to be discovered. I think this is why the thread was revived. In 2012 fewer people would have considered 308 in the same discussion as a 7mm mag. Today they do.
In the 1970's the extra speed of magnum cartridges was more of an advantage than today. Range finders, high BC bullets, and multiple aiming point scopes have made the need for flat shooting cartridges far less important. Better bullets retain energy much better at long range making less powerful rounds more appealing.
At 200 yards a 308 firing a modern very high BC 180 gr bullet hits with more energy than an old school 300 WM firing a very low BC 180 gr bullet. And the 308 does it with 1/2 the recoil. The 300 WM still shoots a little flatter, but that is easier to compensate for.
Of course the better bullets help with the magnums as well. But you reach the point where the technology surpasses the shooters skills. Most shooters are discovering that a 260/6.5 Creedmoor, 7-08, 308 or similar round today will do anything the old school magnums used to do out to 300-400 yards and that is about as far as most guys can shoot. The magnums don't start to become an advantage until you start shooting at 600-700 yards. Even the traditional long action rounds like 270 and 30-06 are much less popular than they used to be for the same reasons.