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.
If you have a high enough reputation with the NCR, you can also convince him to quit and receive 500 caps (no skill check needed)
You can convince him to quit his job without any checks and earn 300 caps
Passing a Barter check (50) here will increase this to 400 caps
You can convince him to quit using a Speech check (50) and earn 500 caps
You can kill him if you have a silenced weapon so long as no one catches you
You can use Terrifying Presence to convince him to quit.
Acquire the Gun Runner's secret manufacturing specifications. (This part of the quest can be refused with no negative side-effects.) Use of a Stealth Boy is highly recommended to get in and out without being noticed or taking casualties.
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, and the only way to complete the quest is by picking the lock to the gate with a Stealth Boy.)
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 you complete the 4th objective, it may affect the ending of "Heartache by the Number" if you solved it the non-violent way.
Behind the scenes
"You Can Depend on Me" is a 1961 single by Brenda Lee, it was featured a year later on her album Brenda, That's All. "You Can Depend on Me" reached #6 on the Billboard Pop Singles chart in 1961.
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.
ps3pc If you have completed "There Stands the Grass" quest, Doctor Hildern might glitch and not accept your parcel. In this case, the console command setstage 000EDB37 15 will complete first stage, and allow you to progress. 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.
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.
xbox360 During the first leg of the quest, Doctor Hildern may never appear, though he does show up on the compass. To force him to spawn in front of you, open the console and type prid 000e8f67 and then moveto player. There is no fix for the Xbox 360 leaving the quest impossible to complete.
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.
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.
pc Unfortunately, when sneaking in the Gun Runners factory without killing any Gun Runners, Blake's inventory will not change.
pc 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.