Buy outCass's contract. Speak with her at Mojave Outpost, at the bar. You can complete this objective via a variety of skill checks and will be rewarded with 500 caps and NCR fame on quest completion regardless of which option you select. Completion of this part of the quest lets you recruit her as a companion. (Killing her with a silenced weapon and undetected will complete this part of the quest, but you will not be paid for doing so.)
Barter check of 50 requires payment of 750 caps from your own pocket.
Barter check of 75 requires you to bring her 12 whiskey.
Both Speech checks (50 and 75) require no payment.
Pick the average lock at the gate (gives negative Karma). Make sure you are hidden, and not detected. Head to the front door then all the way to the back of the building. Grab the information off the computer terminal to the right of the room, and head back out again. Make sure you are still crouching or else the guards will see you and attack. (While crouched, if there are weapons on the workbenches, you can take them and the guards will not notice.)
There is a shift change sometime between 10pm and 11pm (while the gun smiths are conveniently asleep) during which the player can follow a guard through the locked gate. The guard will leave the door unattended briefly to patrol the compound. By moving quickly and quietly, the building can be entered, the data retrieved, and the compound exited before the guard returns to his post. At this point, the gunsmiths may still be awake. If this happens to you wait until around 6am and they will have gone to sleep.
There are claims that this does not always occur. It is incorrect, however, that using a Stealth Boy is the only way to complete the quest when picking the lock to the gate. The entrance is not guarded 24/7, and waiting for the guards to be absent for a moment in the early morning hours will let you pick the lock and enter the building unseen, using sneak mode only (high skill level required, but no Stealth Boy needed). At this time, you will find the interior completely deserted (if you have ED-E's Enhanced Sensors, you can see the absence of NPCs in the building confirmed on the compass), and you will not even have to sneak to the back room. Just make sure you do not waste any time (through the door, straight across the lobby into the back room, use the terminal to the right, and get out), as at 6:00 AM at the latest, the guards will be back at the front door and will catch sight of you if you leave the building after dawn.
Alternatively, You can shoot a guard through the gate and have them chase you to unlock the gate, and then stay away 3 days to cause them to be neutral to you again.
Killing everyone will not stop you from trading with the Vendortron. Be careful not to kill Isaac, as he is involved in an unmarked quest.
If you run in while the guard's back is turned, you can enter sneak mode and hide behind the desk in the lobby. Use the grenade launcher, and fire it at the left-hand corner of the lobby. The workers come out to investigate - you can run in, download the specs, and run back out. However, when speaking to Alice, she will tell you an intruder was detected, and you will not receive the full reward, even though you do not have to kill anyone this way.
If the quest's fourth objective is completed non-violently, it may affect the ending of "Heartache by the Number". In this case, the deaths of both Alice McLafferty and "Gloria Van Graff" at the hands of vengeful Gun Runners.
pcxbox360 Sometimes Henry Jamison may have no dialogue options, just "bye" due to the fact you never received or the game deleted the quest item. [verified]
ps3pc If you have completed "There Stands the Grass" quest, Doctor Hildern might glitch and not accept your parcel. In the case of the Xbox 360 and PS3 for which this bug also exists, there is no known way to correct the lack of an option to give Dr. Hildern the invoice. [verified]
ps3 When you complete this quest and hand in the holotape schematics taken from the Gun Runners, a lot of items/weapons/apparel will disappear from your inventory. This has happened on the PS3 version with the most current update. A way around this is to give all your items to a companion, however this can fail as well. [verified]
xbox360 During the first leg of the quest, Doctor Hildern may never appear, though he does show up on the compass. There is no fix for the Xbox 360 leaving the quest impossible to complete. [verified]
ps3 When you walk out of the office after giving the package to Thomas Hildern there will be none of your HUD showing and you can hear a very deep breathing sound. Also, you will not be able to move or access your Pip-Boy. [verified]
ps3 This may be a design oversight, but when you download the gunrunners' plans to your Pip-Boy, and sneak out, regardless of whether or not you're wearing a Stealth Boy, you will be caught and attacked. [verified]
pc Unfortunately, when sneaking in the Gun Runners factory without killing any Gun Runners, Blake's inventory will not change. [verified]
pcxbox360 Getting the plans in a non-violent way by simply sneaking in and out can sometimes cause the gun runners to become hostile, even after leaving the Gun Runners factory and the policed area. This can be fixed by simply waiting a couple of days. They should then return to their neutral stance. [verified]
xbox360 After completing his personal quest, you may not be able to deliver the invoice to Thomas Hildern, and when you speak to him, your only dialogue option will be "Time for me to go."[verification overdue]