Dealing with Contreras Dealing with Contreras is an in " " . Detailed walkthrough . Siding with Lt . Boyd . You can start this quest by either speaking to Lt . Boyd in the Camp McCarran terminal building or by proceeding directly to Sgt . Contreras ' s computer ( marked " NCR Supply Database " ) in the Camp McCarran supply shack and hacking it ( 50 Science required ) . The supply shack is located in the back of the terminal building via the Camp McCarran concourse ; enter the terminal and go up the escalators then down the hallway to the concourse . When in the concourse bear left down a ramp , and bear right to the door of the supply shack . Contreras ' s computer will be on the upper level of the supply shack . Downloading the weapons manifest and returning it to Lt . Boyd will complete the quest . She will reward you with This Machine and grant NCR fame . By turning in Sgt . Contreras you will drastically decrease his weapon , ammunition , and apparel stores and he may be found in the far right un - openable holding cell . However , he can still be interacted with by aiming at him in V . A . T . S . first without attacking . Since he is one of the best weapon merchants in the game , and since the quest reward ( the unique battle rifle , This Machine ) is awarded to you in two of the three possible conclusions ( siding with Keller will not grant This Machine ) , you should think carefully before deciding . Note that if Isaac at the Gun Runners dies , intentionally or accidentally , you will have no choice but to side with Lt . Boyd . You can also complete this quest if you have sided with Contreras or even Keller . If you downloaded Contreras ' s manifest , or ran his errands and noticed that his " medical supplies " could be used to make chems ( Medicine 25 with Contreras or Blake ) , then you can bring either of these to Lt . Boyd at any time to complete the quest and receive This Machine . Sgt . Contreras will wind up in a prison cell as a result , and he will still act as a merchant though he won ' t restock like other merchants . Siding with Sgt . Contreras . Note : Players may find that there is no dialogue option to initiate this quest when speaking with Contreras , and that the only two dialogue options are to either buy his merchandise or say goodbye . Though the reason for this is unconfirmed , it is believed that completing previous quests with Lieutenant Carrie Boyd or Colonel Hsu may bar players from completing this quest " through Sgt . Contreras " ( In some cases this can be easily solved by selecting the dialogue option to view his merchandise , exiting his inventory , then selecting the new dialogue option ) . The quest can still be completed by downloading the weapons manifest , as detailed in Siding with Lt . Boyd . In actuality , Contreras will not give the quest unless the player character meets a minimum level requirement of 12 ; otherwise he will simply state that the player is too inexperienced to handle his jobs . If you decide to side with Contreras , start this unmarked quest by finding him in the Camp McCarran supply shack . The supply shack is at the back of the terminal building via the Camp McCarran concourse . Enter the terminal , go up the escalators , down the hallway to the concourse . When in the concourse bear left to a down ramp , and bear right to the door of the supply shack . Speak to Sgt . Contreras about his supply which will lead to a Speech / Barter check of 50 . You also have the option to pay 50 caps . Contreras will then ask you to speak to Isaac outside of . Isaac should be located near or at the reloading bench to the right of the Vendortron at the Gun Runners storefront ( If Isaac isn ' t there , he may be in his house directly to the east of Gun Runners , behind the Hostetler home . If he isn ' t there either , check the Bugs section for this quest ) . Speak to Isaac and you ' ll either have to pass a Speech / Barter check of 80 or you can give him 100 pieces of junk metal ( tin cans , hot plates , metal pots , pots , pans and scrap metal ) . If you must scavenge the metal pieces , the Aerotech Office Park ( suite 200 ) has over 100 tin cans ( bent and regular ) . Boulder Beach campground and Broc flower cave each have around 50 tin cans ( bent and regular combined ) ; the latter area ' s tin cans can be found in a corner of the makeshift lab where the Ratslayer is found . REPCONN test site has around 30 tin cans and 40 scrap metal . Once you ' ve gathered enough , return to Isaac . Contreras ' next errand will be to obtain medical supplies from in the Crimson Caravan Company . Blake can be found around the center of the camp , next to the shelves with items on them , during daylight hours . With 25 Science or Medical skill you can observe for Contreras that the supplies he ' s acquiring could be used to make chems , or you can point the same thing out to Blake ; however , doing so to either man will have no effect on the quest whatsoever . Once you have the supplies , return to Contreras . At this point you can tell him about the chems and threaten ( no Karma loss ) to tell the NCR and he will give you 100 caps to keep your mouth shut , after you give him the medical supplies he ' ll tell you he needs a " couple days " before he has another mission for you . Waiting for 26 hours is sufficient to trigger the next quest . Contreras will then ask you to deliver the medical supplies to a man named in Miguel ' s Pawn Shop . He ' ll also give you a pass phrase : " I ' m looking for some betting advice " to speak to Price , and he ' ll tell you what pass phrase Price should say to you in return . When you enter the pawn shop though , Price is nowhere to be found ; instead , speak the pass phrase to Keller . Keller will not know the correct response . From here , you have a few options : If you return to Contreras before killing Keller , you can get 150 extra caps upfront with a Barter check of 50 . Killing Keller . If you choose not to make a deal with Keller , you will be forced to kill him to finish the quest in Contreras ' favor . Killing him will result in NCR infamy . To avoid this : Return to Contreras after killing or making a deal with Keller . Settling things in Contreras ' favor , he ' ll award you with This Machine and the next time his inventory restocks he will have a wider selection of items . Siding with Keller . If you side with Keller , you will not be able to obtain This Machine from Contreras , but you will still be able to side with Boyd afterward , turn Contreras in and obtain This Machine from her . To complete the quest in Keller ' s favor you must have already completed Contreras ' first two missions , then when he sends you to speak to Price in Miguel ' s Pawn Shop Keller will be there instead . The most direct way to complete the quest in Keller ' s favor is to give him the medical supplies . Once you do this , he ' ll threaten to arrest you , you must claim you ' re innocent and blame Contreras . Keller will be pleased that his suspicions of Contreras have been confirmed . You then have to pass a Speech check of 60 or a Charisma check of 7 to convince him you didn ' t know what you were carrying . Keller will let you go free , but says Contreras will be executed . At this point you can leave , which will get Contreras arrested and you will lose access to his expanded inventory . With a Speech check of 80 , you can convince Keller to have Contreras become his informant . Or , with Barter , you can bribe Keller for 250 caps to throw his lot in with Contreras - despite the bribe , the plan remains him becoming an informant . Lacking a Barter skill of 60 , the bribe attempt will fail , but you can then offer Keller 500 instead . Keller will accept and ask you to bring the deal to Contreras . Return to Contreras and inform him that Price is being held by the NCR and a Ranger has taken his place . If you were forced to give Keller the medical supplies , Contreras will demand that you kill Keller ( refer to the bug where , even when killing Keller , the dialogue option with Contreras is as though a deal has been cut with the ranger - the relevance of this is regarding Contreras ' special stock not seeming to become available ) . You could return and kill Keller , in which case consult the " Siding with Contreras " section above . If you are determined to side with Keller , then with a Speech of 80 or a Barter of 70 you can convince Contreras to cut a deal with Keller . Contreras will ask you to speak to Keller once again ; you must pass a Speech or Barter check of 80 to get Keller on board ; otherwise , the only dialogue option left is to attack him . Convincing Keller will complete the quest , awarding you 80 XP but not This Machine ; Contreras will still deal with you , but it appears that you do not gain access to his special stock .