I have 4 factory Remington 700 ADLs. .243, 25/06, .308, and 7mm Remington Magnum. They are all identical except for caliber. I use them all for hunting at distances of less than 200 yards and am looking to shoot to 600 yards with one of them. Which of these calibers should I play with? I know that the factory stocks suck so I would be looking to upgrade the stock and scope on the one I pick. I hand load my own bullets so please consider that with your recommendation. Which caliber would you pick?