In this page you can find a detailed description of "Locked and Loaded" achievement that you can unlock in Get Even. You get this trophy by getting three ammo clips during a single visit in the Asylum while playing as Black.
A single visit means the time spent in the hospital from the moment of completing the last "big" memory (those, that have their own boards in the evidence room) to starting a new big one. Black, during his campaign, visits the building B twice in this way and in the later part of the game he also visits the building C twice.
The first chance
The first chance to unlock this trophy appears during the exploration of the second part of the building B. The first ammo clip can be found shortly after solving the puzzle with the locked passage that requires a four-digit combination (the area near John Keating's cell). After unlocking that passage you should visit one of the nearby rooms. The ammo clip is in the dark room presented in the picture above.
In this next area you may have to deal with a hostile patient. After shooting him you should continue your journey until you reach the area with many new tracks. Here, you must check the side room with a TV on, you can see it in the picture above.
The last clip from the "set" can be acquired a little bit later, after completing a level in which you travel in void between rooms (this level doesn't count as a "full-fledged" memory). When you go back to the hospital you can continue walking through it and you should visit all rooms that you pass by. The ammo can be found in the place presented in the picture. You also visit this room before you reach a console that unlocks a passage that allows you to go further.
The second chance
The second chance for unlocking this trophy appears during your first visit in the block C. Go past Boyce's cell and use the stairs. After that you can find an ammo clip. It will be behind the bars in the place presented in the picture above.
Soon, you will be attacked by a hostile patient. After eliminating him you should look around for the second clip that lies next to the flare on the chair presented in the picture above.
The last, third, clip is also in the area and you can find it lying on the desk presented in the picture. When you take it you will receive the trophy. Warning - Get all ammo clips before you use the building's exit that leads to the Asylum gardens.