Has a hard time with mulies? with a 270? Boy he needs to go back to hunting school. A good 270 round will still retain around 1700 lbs ME at 400 yards. Darn bullet proof critters. They will be hunting us soon.
As tough as the game is getting I quess the 30-378 should be your minimum choice. The deer might take the little 300 WSM and wrap it around your neck
. Or worse.