Re: If you only had one
Personaly. If its a one gun for all, then you have to be able to buy factory ammo everywhere. Considering that and your want for 600yd capibility I would choose the 300win. Federal, black hills, TTI, freaking everybody, makes match ammo for it, it doesnt recoil redicuosly like the big 300's. and for what you wanting the extra power wont help you all that much.
JMHO, a 300winmag, made right in a medium weight rifle, with a 26-28in medium barrel, and mid power scope with repeatable adjustments, is about the perfect all around gun.