You've committed to the AR-10 platform — now comes the question that keeps every builder up at night: .308 Winchester or 6.5 Creedmoor? These two cartridges dominate the AR-10 world for good reason. Both are proven performers, both fit the same action, and both have passionate advocates willing to argue their case at the range. But they are not interchangeable choices. One is built for a different job than the other, and picking the wrong one for your intended role means leaving real perfo …