400 meters at 50 pound deer? Why the 308? the 6mm-6.5mm Creed perfect for that. The other loads that shoot better why wont they work on 50 lb deer? Have you proved accuracy of your different loads at 300-400 meters. For hunting rifle shoot only 3 shots groups because hunting never likely to shoot more than that. Also with 3 shot groups will the first cold bore shot go in the same place? BTW did I say try your ammo at 300-400 meters to see what that looks like.