First of all I have zero experience with anything larger than mule deer, white tails and wild hogs. So no way I can advise for elk, moose, bear, etc. I have a pretty good and 40+ years experience hunting with both the 30.06 Spr. and 308 Win. I hand load for both and have shot 1000's of rounds of each at the range. In my opinion, for us average shooters accuracy is a function of too many inputs to be cartridge only. By far, No. 1 of these is us-n's ... the shooters. In truth, there is indeed a great dependency in the accuracy upon the quality of the rifle, a good trigger and having ammo that matches the idiosyncrasies of that particular rifle. Having said that, there seems to me to be something about the 308 Win. that seems optimizes the performance of many, many quality bullets and powder charges. Maybe it is the shape of the case ???

From a ballistics stand point, which any reloading chart will confirm, the 30.06 Spr. starts to outshine the 308 Win. when the bullet weight exceeds about 165 gr. In the 130 gr. to 165 gr. bullet weight, the two are very, very close in every way. I have found that my 308 Win. rifle "likes" a 165 gr. bullet at about max load best. My 2 - 30.06 Spr. rifles do great with the 165 gr., however 1 of them will darn near cloverleaf 180 gr. bullets pushed at near max as recommended by the Speer reloader manual I have. This is true in all 3 of these rifles for both flat based and boat tailed spitzers.

My personal hunting rifle of choice on all but the little bit of western hunting I have done, where shots could be 400-500 yards, is my 308 Win. However, I would think that if you are going to "one rifle" yourself, the 30.06 Spr. would be a better choice. The longer case will handle longer bullets better. I am guessing that bullets in the 180 gr. and up in the 308 Win. case are so long that they start to take up space that could otherwise be used for additional powder charge.

Truth for deer, either would be great. For moose and elk, I'd say ditto. For big bears ... ???