RE: 338 Win Mag or 300 Weatherby
accuracy depends on the rifle's and loads quality. If the 338 mag is accurate at a 100yds then it will probaly accurate out to as far as you can shoot it. The thing would boil down to tajectory between the two. They both have optimum energy. The 300 weatherby would give you a flatter trajectory. The down side to it is the price of the cartridges.