The lights are on
The Alien Blaster is located in the top right hand corner of the map , if you zoom in and count the squares it's the 3rd one down and on the border of the 5th and 6th ones in from the right. An easy way to find it is to go due north along the power lines from the MDPL-13 power station (5th square down 6th one in from the right ) the 3 smokestacks make a good landmark ( dont forget to go inside for another unique weapon the Fisto powerfist and a nuka cola quantum ) follow the powerlines north keeping them on your left until you see the broken pylon , follow the direction it's pointing (the alien ship apparently clipped it when it crashed ) until you start getting radiation poisoning . Next to a small cliff west of the road , just beyond where you can see the power station smokestacks to the south , you should find the crashed UFO . This weapon will vaporize almost anything in the game with one or two shots , make sure you collect all the ammo in the vicinity it's very rare , you cannot buy it , and there are only 2 other places I've found it . One is the train station by Tenpenny tower , the other is the crater with the truck in it by Fort Bannister (there is supposed to be another blaster here , but I can't find it) . You cannot repair the alien blaster yourself , but anyone who repairs weapons can repair the alien blaster for you. Another superweapon that's easy to get is located in Girdershade . Girdershade can be found in the bottom lefthand corner of your pipboy map. If you zoom in till you can see the grid it's in the 4th square up from the bottom and the 2nd one in from the left. Only 2 people live in girdershade Sierra Petrovita and her 'boyfriend ' Ronald Laren . Talk to Sierra and take her tour to activate the Nuka Cola Challenge quest . Next talk to Ronald if you win the speech challenge he will pay double for each quantum cola you find( this is useful if you need caps) finish the quest then kill Ronald he carries a unique double barrel shotgun called The Kneecapper which does significantly more damage than a regular one if you dont care about the caps you can just kill him right away . By the way be careful not to use The Kneecapper to repair a regular shotgun because if you dont save often its gone forever ( i save about every 15 to 20 mins it takes seconds and saves major headaches if you die or F up)
The Reservists Rifle is a unique sniper rifle carried by the Drifter . You can find him at the Dickerson Tabernacle Chapel (top left hand corner of the map 4 squares down and 4 squares from the left ) . He is sitting in the rafters looking out the front of the building ,sneak up behind him and kill him , he also carries the Druids Hood and coordinates to find Oasis which will automatically be added to your map.
The Microwave Emitter is a mesmetron special weapon that can be obtained when you complete all of the main quests in the Point Lookout add-on. After you finish the last main quest go to the end of the room to the exit and right beside the ladder should be a workbench and on top of it is the Microwave Emitter and a few power cells. (Note: The Microwave Emitter cannot be used to enslave people, but when it strikes a critical hit it disintegrates enemies.)
The Destabilizer is a very powerful form of the Alien Disentegrator in the Mothership Zeta add-on. In the experimental weapons lab there is a small shooting range where you can also obtain a perk as well as the weapon. Right when you enter the room, the Destabilizer will be in a crate next to the door. The Destabilizer can be repaired by Alien Disentegrators and uses Alien Power Modules for ammo.
Callahan's Magnum is a unique Magnum obtained in the Broken Steel add-on. The only way that this pistol can be obtained is by choosing to bomb the Citadel at the end of the main storyline. Once you reach the destroyed Citadel, about five Brotherhood members will attack you. After kiiling them, go inside the destroyed Citadel and jump to the bottom of the crater inside. Look around for an untouched door and use it to enter the armory. Once inside, head up the stairs and look around for a safe and intact computer. Inside the safe is Callahan's Magnum.
The Terrible Shotgun can be found in Evergreen Mills . Located north east of Girdershade and north of Tenpenny Tower , Evergreen Mills is home to a Raider gang who have managed to capture a Super Mutant Behemoth .DO NOT charge in guns ablazing , you will die fast . Evergreen Mills is in a canyon with a trainyard , and only one entrance . After repeatedly dieing I decided not to use the front door so to speak , opting instead to circle around and station myself on the ridge to the east . From this vantage point you can get a clear view of the area ( a stealth boy helps here , the Raiders are vigilant ) . Find a spot where you can get a view of the generator on the Behemoth pen ( sniper rifle would be useful here ) . Blow up the generator to release the Big Boy , he will return the favor by Hulk smashing everyone in sight . Be patient and let him do his job , when the Raiders are dead make your way down the hill to the trains . Big Boy will probably still be alive and deadly ( though hopefully weaker ) . Wait until he is around the corner to the left , then dash to the last train on the left and climb on top , you will be safe here and if you bring a missle launcher , should have no trouble taking him down ( oddly you never get any experience points for killing a Behemoth ). Ok now go inside the mill , there are Raiders inside but not as many as outside . Clear out the first area , then go inside the foundry / bazaar area to the left . All the way at the top you will eventually fight your way to Smiling Jack the bartender , he won't attack you so talk to him , then murder him in cold blood . Loot his body , at last the Terrible Shotgun is yours , take his key his locker has some good supplies . Also to the right side of the bar area is a little alcove with a desk , jump over the desk there is a safe underneath , and the Barter Bobblehead waiting for you on a shelf .
dont forget about the terrible shotgun that u get from smiling jack or colonel autums laser pistol at the jefferson memorial