Not equal, but closer than you'd probably think. I don't handload for either caliber, but a quick look through my Lyman manual shows that you could push the same 200gr bullet to nearly 2700 FPS in the -06, or just barely over 2900 in the 300 Win Mag (tested with a 24" barrel in both cases). So just a bit over 200 FPS difference.
This is all theory of course, but using all the same external data, according to JBM:
From the 30-06:
- Your bullet is supersonic to just barely beyond 950 yards. Just past that, it reaches the transonic zone (roughly Mach 1.2) and flight may (likely will) become erratic and unpredictable.
- At that 950 yard mark (your max reachable range with this load), the bullet is carrying 841 ft lbs of energy, and traveling ~1376 FPS - just barely over Mach 1.2. I say max reachable because, though the bullet will continue to travel, your ability to place it as desired no longer lies solely in your skill as a shooter.
- - - - - - -
From the 300 Win Mag:
- Your bullet is still supersonic out just beyond 1100 yards
- The bullet carries 951 ft lbs of energy at 1000 yards, and is traveling at 1463 FPS
Not a HUGE difference downrange. The limiting factor for terminal performance is going to be meeting an adequate velocity to provide consistent expansion of the bullet you use. You can find the manufacturer's suggested minimums on their websites, depending which round/s you select. Then use a
correctly coded ballistics calculator with accurate data and find max effective range for your load. As so many others have said, whether or not you can get the bullet there will be up to you.
In theory, you could start by researching and end up determining the ideal caliber for what you want to do. For instance, say you know you want to be able to hunt (even if you never DO, you want the ability to do it) a specific game animal at 750 yards. Or 1200 yards. You start researching the type of bullet you need for that specific game animal, whether it's a cup and core bullet or something bonded or whatever. Then you look up load data and figure out which caliber rifles will push that bullet to varying velocities, and you plug those velocities into a calculator along with the elevation where you'll be hunting, expected temperatures and humidities, everything you can anticipate. Does caliber X push that bullet fast enough at whatever your max distance is to meet manufacturer's suggested minimum velocity for expansion? If not, that caliber won't work for you. Try again. Not the most effective way to go, and will take a lot of time, but you can figure it exactly what you need without ever spending a dime. Then once you get it, you practice and practice until you're able to perform, but you know going into it that the gear is up to the task. All that said, try and kee in mind that taking a life isn't a math problem, and life doesn't always turn out the way we expect. You could face any number of surprises. People have been killed with air guns, and others have been shot by large caliber rifles and survived.
Personally, I wouldn't be buying a rifle any time soon. Use the 30-06, get a quality optic, start doing your research, and spend more time behind your rifle. No reason to blow money on a new gun yet. If that money is burning a hole in your pocket, add it to your budget for the glass, and on ammo components.