Idk if anyone is having issues with the Vanguard armory, But after you put the code and access the tower, You go to the right of where you are dropped off, continue into the tunnels, then afterwards you make a right before you hit the stairs of which you'll see someone named "Vanguard Quartermaster" in which he'll sell you a auto rifle, hand cannon, sniper, shotgun, helmet, and rocket launcher, each one pricing at about 250 glimmer.