Megaton armory

Behind a very hard locked door is the Megaton Armory, home to all of Megaton's spare ammunition and the computer terminal used to control both the trusty Deputy Weld, a protectron guarding the front gate, and the Mister Gutsy robot named Deputy Steel, he himself guarding the Armory.

The Key
Sheriff Lucas Simms has the key to the armory which can be obtained without making the town hostile early in the game simply by stealthily pickpocketing him or letting Mister Burke kill him during the Power of Atom quest, then looting his corpse. Alternatively, you can kill Simms but the town will then become hostile.

The key is named "Lucas Simm's House Key", so don't be fooled; it unlocks both Lucas Simm's House and the Megaton Armory. It is also essential to sneakily enter the armory with a Stealth Boy already active because Deputy Steel, the aforementioned Mister Gutsy robot, will attack you for trespassing. If caught Megaton's citizens will become hostile, forcing you to leave the city for three days to let everyone forget your crime.

Please note that the Deputy's deactivation terminal requires the ability to hack Hard level terminals (75 Science skill).

If you do not have a Stealth Boy, cannot hack the terminal or defeat the robot, try running in and grab all the weapons on the table, and run right back out. Fast travel to another area quickly to avoid the robot alerting the townsfolk, and then travel back to Megaton. You may need to heal at this point. Repeat the process to pick the room clean.

Citizens shocked
If you are seen entering the Megaton Armory, or if Deputy Steel leaves the armory while attacking you, the whole town will become hostile and either flee or attack. Leaving town and waiting a day will calm down Megaton's citizens, and the intrusion will be mostly forgotten.

If you disable Deputy Steel using the Terminal, looting the armory will not cause any reaction from the citizens. They behave as though nothing has happened.

Loot

 * Chinese Assault Rifle x 2
 * Combat Shotgun
 * Hunting Rifle x 3
 * N99 10mm Pistol x 2
 * 10mm Round x 8

There are also four metal boxes, a cabinet, a locker, and an average safe (requiring 50 lockpick), which may yield different loot from game to game. Recorded loot from these containers are (including cameras used for a repeatable quest item in Broken Steel), AEP7 Laser Pistol, Scoped .44 Magnum, .44 rounds, a fourth Hunting Rifle, and a Nuka Cola.