Any bullet you choose for a 300 mag will "over penetrate" a deer. Although i prefer to have a bullet "over penetrate" and give me two holes to drip blood instead of just one.

Personally I would choose the 180 grain accubond. Winchester and Federal both load this bullet so which ever one shoots the best in your rifle.Itis soft enough up front toexpand reliably in the smaller game animals like deer, antelope, etc...and the thicker wall at the rear of the bulletand bonded construction will assure esxcelent penetration in larger animals like elk and moose.

Ballistically there isn't a hill of beans of difference between a 150, 165 or 180 grain high BC bullet. At 400 yards you are only talking about 3-4" advantage with the lighter weight bullets.