RE: over kill
The longest shot I've ever taken was on a 5x5 mule deer on public land in South Dakota. It was 500 yards. I pulled out my range finder, made my corrections on the scope, adjusted the bipod and dropped him on the spot. The 180 grain Accubond bullet entered high behind the shoulder and stopped under the hide on the opposet side.
That would have really pushed the limits of my 30-06, but my .300 win mag did it with no problem. Obviously you don't need a magnum, but it sure is nice sometimes.
Now that I live here, I'll probably never have another chance to hunt out west, but I see no reason to hunt with any other gun. I've already got one that works just fine and shoots better than any other gun I've ever owned.