I would choose the .308 winchester. Why? It is a very versatile round. It has bullet weights from 110 to 220 and many different bullet styles and loadings from about every manufacturer. It is usuallyvery accurate. You will still get good velocities in the 15" barrel. Factory ammo can be found just about anywhere if you dont handload. Military surplus for practice at cheap prices.Hornady makes light magnum ammo but the short barrel may not do it justice. Can use chrony and see. Doesnt hurt but inthewallet for a box.Ithaves managablerecoil. Some use the 30-06 but I cant see any advantage in the 15" barrel. All that powder couldnt get burnt.Also, you can get good deals on usedbarrels that probably havent seen too many rounds through them.I hope this helps.