Im having a problem with the outcasts! Every time I open the armoury door, I take some stuff and when I pick up a random item, they all go hostile! Why, Im not sure if Im taking to much stuff or a certain item. HELP!

That supposed to happen. If you open the door and just stand at the entrance and listen, you'll hear the outcasts talk about "Why should he have first dibs" or something like that, and after a few seconds they'll start to attack you and the outcast that let you in. So it'd be best to wait for them to start attacking, kill them, then get the loot.

The point is that Sibley doesn't want you getting any loot from the vault, resulting in a verbal and then armed conflict between the Outcasts. Some are on your side (or was it just the two) and the rest want to take you out.

I hurriedly whip mines and nades out the door of the room you are standing in, grab a mini-gun, and hose down the area.