I will be Hunting deer will be 20 yards - 300 yards. The 300 win mag is to much HP and ton of meat damage. What caliber do you use with, that don`t destroy a lot of meat.
Sounds to me like a .270 Winchester would be in order, use any good 130gr(I like Speer Grand Slams and I just bought 200 Nosler Partitions from SPS). Close to the same trajectory as your .300, but with a LOT less recoil, BIG medicine on whitetails.
