This is a very easy achievement to unlock. In Chapter 4, you'll be heading to the Admiral's quarters. You can get this achievement before you enter the quarters and begin the cutscene, or you can wait until after you've enjoyed the narrative moving forward. On the wall just outside the room where the Admiral has scrawled markers all over the walls is a Buck's head mounted like a hunting trophy. Shoot it and the achievement or trophy is yours.
If you still can't find it, here's a youtube video:
Star Citizen is an upcoming space trading and combat simulator video game for Microsoft Windows. Star Citizen will consist of two main components: first person space combat and trading in a massively multiplayer persistent universe and customizable private servers (known as Star Citizen), and a branching single-player game (known as Squadron 42). The game will also feature VR support.
