ORIGINAL: FF/EMT
What I am looking for is a rifle that would mainly be used for Whitetail/Mule deer, that could also be used for elk if the opprtunity ever presents itself. I had been looking into the 7mm mag, but also have a friend telling me to go with the 300 win mag. Like I said earlier this rifle hunting is fairly new to me, so thanks for bearing with me.
Tom
With the the Magnums you've mentioned, the main benefit is extra range. By spitting the bullet out of the tube faster, the projectile will drop less in the same distance than a bullet shot from a non-magnum cartridge. For instance, the .300 Win Mag in the following example shoots roughly 5½ inches "flatter" than the .30-'06 does at 300 yards.
http://www.remington.com/products/ammunition/ballistics/comparative_ballistics_results.aspx?data=R300W2*R3 0065
This also translates into terms of "power". If you'll notice the part showing energy in ft.-lbs.,the .300 Win Mag will be carrying the same amount of energy at 400 yards, asthe .30-'06does at 300 yards. Naturally, if you're shooting them both at the same distance, the .300 Win Mag's bulletwill have more energy.
Now, whether this makes the .300 Win Mag "better" than the '06, has been the subject of volumes of debate for decades, and it's not likely to end anytime soon. They'll both kill deer awfully dead, awfully quickly. And they've both been proven to be wonderully effective on elk, too.
What's not debateable, however, is that the .300 Win Maguses a lot more powder to do what it does. The result is greater muzzle blast, and more recoil. Also, many manufacturers equip rifleschambered for magnum cartridges with longer barrels, so there canalso bea difference in weight and handling characteristics. You'd do really well to go to your local gun range and shoot both a standard and a magnum rifle before you select one.
When choosing between the two, I'd ask yourself what the hunting conditions are like where you'll be most often. Are you shooting across wide-open plains, or do you come across your deer in ravines or timber, where the shots are closer?. What's the average distance that you shoot, or will be shooting? What's the longest distance that you actually practice shooting? If you find the answers are often 300 yards or more, thena Magnum cartridgewill probably be a better choice. If you're usually under 300 yards, I'd recommend going with a standard cartridge.