The180 grain load is quite possibly the best . 300 Win Mag ammo for elk, bear, and moose hunting. The 165 grain load will also work for larger game like elk, but it’s perfect for bigger deer and bear. That high velocity 150 grain load is great . The .300 Winchester Magnum (7.62×67mmB, 7.62x66BR) is a belted, bottlenecked magnum rifle cartridge that was introduced by Winchester Repeating Arms. Buy 300 Win Mag Ammo For Long Range