Center of Mass
You don't fool around with fancy trick shots. Straight to the midsection and down they go. In V.A.T.S., you do an additional 15% damage with attacks targeting the torso.”— In-game description
When targeting the torso of an enemy in V.A.T.S., an additional 15% damage is dealt.
Behind the scenesEdit
In terms of weapons handling, center mass refers to the center of a person's chest or torso, which is the middle of the visible mass, making it the most likely place to score a hit. The center of mass is not only the largest target but also where important organs are, so it's generally seen as the priority target, lacking the difficulty and improbability of a shot to the head.