Found in the engine room during the generator-destruction phase of the main quest. Walk down the stairs and follow that corridor until you get into the big open area. Take a sharp left in the open area, and then the first left on the same wall you came in from. Go in that room and then follow the small corridor and at the end it will be lying on a table.
Found on a bed in the back of the Supply plant in The Pittsteelyard close to a single steel ingot. Enter the Supply Plant, then go east through the hallway. Turn north and continue until you reach two exits. Take the left. Continue through the passage, climb the stairs, and eventually exit into a large room. The bed is on the left as you enter.
Found in the waste disposal area of Zeta, accessible through the maintenance level (which can be entered only during the quest "Among the Stars"). It is at the outer southwest area in a closet full of medical supplies
Found in Anchorage Memorial inside the utility room with a broken door. Enter the Memorial Service Entrance on the east side of the memorial. At the junction, turn left and it's the second door on your right. The door can be fixed by finding the door component, with Repair skill of 35 or higher. Without the component a repair skill of 95 is required to open it.
Found in a hard-locked safe in the ruins of the Citadel if you choose to destroy it during the quest Who Dares Wins. Enter the door at the bottom of the crater, head up the stairs, and enter the cubicle against the far wall.
Found in the Museum of History Lower Halls. Go up the stairs into a room with several broken display cases, in the back left corner of the room will be a door that leads to the Museum of History Offices. After entering, go to the top of the stairs. Take a left and then a right. Go to the end of the hall, through the prison door (locked Very Easy level) and into a big room with a turret. In this room you'll find a stair case. Go up these stairs. At the top of the stair case you will see a large hole in the wall. Go through the hole in the wall and in the back left corner of the room you will see the body of a dead raider on the ground, and the display case with Lincoln's repeater inside.
Found in Dave's office in the Republic of Dave capitol building, in the safe next to his chair. Dave's special key is required to open the safe. You can pickpocket Dave to find the key, you can complete the Election Day unmarked quest to get it, or you can get it through dialogue options and speech checks if you are on the quest You Gotta Shoot 'Em in the Head.
Carried by Sydney. It can be obtained by either killing her, letting her die during the quest Stealing Independence, or finishing the quest and afterwards giving her "A note from Little Moonbeam's father".
Found in Franklin Metro utility, beneath Falls Church/Mason Dst Metro. Navigate the utility to where the tunnel goes down into the water. Go into the water and then go left through a broken passage in the tunnel. Swim to the right and go up the ramp. Continue down a hallway filled with radioactive barrels. It lies at the end of the tunnel.
Found in the weapons lab, where you can spawn brahmin for the drones to kill. Enter the room and kill the drone for the weapon. This item is listed as unique, however, it is possible to get two of them. Where you find the drone mentioned, there will be another one close by that also drops the weapon.
Found in a small room located in a hallway near the entrance to the weapons lab on mothership Zeta, after beaming up from the space walk section and proceeding through the observation deck. The room can only be accessed by using an alien door terminal that requires 75 Science to activate.
Found in the cargo hold of mothership Zeta, in a safe locked by Reid Underwood's terminal (hard). The terminal is found by first going to the Research lab door, then northeast. The safe is found in another area among several piles of rubble, next to a machine that is dropping items into a pit.