I've never shot a moose but I doubt one would be any better than the other. The most important part is the bullet. That's a lot of animal but I understand easy to kill. In a 7mm mag I'd use at least a 160gr bullet better a 175 gr. In the 300 mag I've always felt the the best bullets were 200gr and up. I'm ssure there are people around shooting them with lighter bullets but I wouldn't care. Now if I did go moose hunting now, I'd take my 30-06 with 180gr bullets.
It is six one and a half of dozen of the other. They are both good. If it was me & that was the only 2 choices I would take the .300 because I like the 30 cal and am not overly fond of the 7 Mag. It will do the job quite nicely but I never did develope a liking for it.
There are still some who insist a scope is not needed for the type hunting they do, ignoring the advances of the last 150 years in optical sights. (Even the ultra-conservative US Army has adopted optical sights.) The idea that in some special circumstances open iron sights or aperture (peep) sights might be more useful is not lost on me, but with the inevitable advance of age comes the reduction in visual acuity needed for using iron sights.
I believe that many who completely resist the idea of...