I would agree that the extra horsepower of the 300 RUM would serve you well. At the ranges youare wanting to hunt at, out to 650 yards this would be in my opinion a better round, especially for elk.
For deer, there is no real need for a 200 gr bullet but there is nothing wrong with them either. To much penetration is never a disadvantage in the field.
Still I like the 180 gr Ballistic Tip, Ballistic Silvertip or Accubond for strictly deer hunting loaded to 3400 fps.
For elk, I would use nothing but the 200 gr Accubond in a factory rifle because of the performance this bullet is getting on game at longer ranges.
Your biggest problem will be getting a factory rifle to be consistant enough for you at 650 yards for taking deer size game.
Get a rifle designed for longer range shooting, such as the Sendero or something on that line. A light weight sporter can be used at those ranges but they are no where near as easy to shoot at longer ranges.
You may also need to have the rifle accurized to perform well at these ranges.
Once your rifle will handle the job, then you need to get prepared for those shots and this is only done with alot of range practice and ballistic studying.
If you want to hunt at 650 yards, you should practice at 800 yards in my opinion. DO not shoot at 300 yards and then go off a published ballistic chart.
Prove the numbers at teh range in the temps you will be hunting in and record all your data.
This is not real critical for hunting out to 400 yards but when pushing a factory rifle to 500 yards and beyond, you need to have your ducks in a row before the shot opportunity arises.
I also agree with the muzzle brake, I highly recommend the Holland QD brake for my customers heavy kicking big game rifles but most popular brakes will reduce the recoil noticably.
I just prefer the Hollands because they have a solid bottom and are designed to be fired from prone field postitions without covering the shooter with ground debris.
Good Shooting!!
Kirby Allen(50)