We don't know the depth of your shooting or handloading experience, but if it is from the shallow end of the pool a .30/06 or a .308 might be better choices until you get your feet wet. Aside from the obvious recoil and blast issues, factory ammunition costs increases exponentially when you move from a .30/06 to a .300. Personally, if I chose to put up with .300 magnum recoil, I would opt for a larger caliber with heavier bullets. IMHO bore size trumps velocity, so if I need more than what I can get from a .30/06 I look at a medium or a big bore rifle. A medium bore can produces .30/06 trajectories, but will produce larger wound volumes, and penetrate deeper. This "advantage" is pretty much lost on North American game in hunting scenarios, but it "might" give you the edge if you are engaged in protection work. Under normal hunting conditions, if the '06 doesn't do it, the .300 won't either. Where the .300 shines is when shooting at extended ranges.
Just to reiterate though, while I often use a larger rifle, I don't feel unarmed when I'm packing a .30/06 rather than my .375 for bear work. The combination of bullet weight, velocity, and recoil makes the .30/06 the best choice for my wife to use for bear protection, as opposed to bear hunting.
I prefer bolt action to gas guns, but clearly the semi-auto has certain advantages. Not the least of which is less apparent recoil, and an action that will cycle reliably regardless of the state of mind of the shooter.
In the end you are going to buy what you want, but again I would council you against a .300 magnum. If you choose to ignore that advise, I would urge you then to consider handloading so that you can tailor your ammo to your comfort level which will enable you to pay more attention to practical marksmanship and less to the mystical qualities of the .300. When you can shoot 4" groups at 200 yards from field positions, you ready to hunt with your magnum.