Binary Rifle Kill
From Halopedia, the Halo wiki
Binary Rifle Kill is a medal awarded in Halo 4 multiplayer for killing an enemy with a Binary Rifle. The medal is awarded for both head and body shots. The player will also be awarded the medal if an AI passenger in a vehicle they are driving kills an enemy with a binary rifle. It is represented by a beam rifle's reticule on a grey four-pointed star.