I have killed my last couple elk with the 7 Rem Mag and found its performance more than adequate. My advice is to use the rifle you are most comfortable with. Bullet selection and shot placement erases any practical terminal difference between these two cartridges. As mentioned above, both of these cartridges are excellent choices for elk hunting with a quality bullet and well-placed shot.
Here, this will help you out I am sure, lol
Mike Eastman likes the 7MM Mag.
Guy Eastman likes the .300 Win. Mag.
Not that my opinion matters much, but just for the shear fact that you can get more bullet weights in factory loads, I would lean towards the .300 Win. Mag. Either way, I have personally seen both calibers put elk down with authority. If you choose the 7MM, stick with the heavy for caliber bullets like 160 grainers and for the .300 Win. Mag the 200 grain rounds work great for elk and the 180's for everything else. Just my two cents...
Eastmans' Hunting Journals
I'd try a 300 with a good stout 180 or 200gr load and see if you can handle the recoil before purchasing one. A limbsaver pad can really help or a brake, but that adds length to your barrel without improving ballistics.
I personally used a 270 last year, I shot a 300WM with hot 180gr loads at everything from varmints up for years and developed a flinch doing it. I have found that now I shoot better with a 270 win or 264WM, pushing a 140gr bullet to 3000fps has been getting the job done at a recoil level that I can manage well. I practice more and shoot better this way, and where the bullet lands is still more important than how big it is. I'll have to pass some tough quartering shots I may take with a 200gr accubond from a 300WM, but I'm ok with that.
7 mag does a great job of pushing the 140gr bullet to 3k with a moderate load for a modest recoil deer rifle, and can push a 160-168gr the same speed if you need the extra performance. I did that for a while with a Colt light rifle I had, practiced most of the year with the 140's then stepped up to the 160's preparing for the elk hunt. The guy I hunt with used a 7 mag last season with the 150gr accubond long range bullets. He put 3 shots through the lungs of his bull before it fell at 420-450yds. All passed through and looked like they performed well. He was trying to shut the bull down before he dropped off into the nasty canyon he was bedded along, didn't work.
Placement is the key to anchoring them, just like any other animal. High point of the shoulder with a bonded bullet should do just that. I can shoot our rabbit sized WT square behind the shoulder with 180gr NBTs and them jokers are going to run.
I currently shoot factory Remington Core Lokt 150g. I've had great success in the whitetail world with this setup. If I need to step-up to a larger grain bullet or a better one I will?
I believe you have the right ammo and even though a heavier Core Lokt may be recommended I would stay with the same bullet you have been shooting because its enough for elk and you would not have to make any mental changes as ballistics go.
I would for sure for elk. But it's still all about shot placement.
I don't Break the rules, I Modify them.
The 150 Core Lokt is a good bullet for elk. I would stick with it if it shoot well in your rifle. Just put it through the goods.
I generally go with 160 -168 grain bullets in the 7RM, but more for the ballistic coefficient advantages than the terminal performance.