having played the game through, i went back to an earlier save and for the hell of it decided to see if i could take out everyone at the Duty base. i managed it pretty well, though was a little guilty when the stalkers joined in against me and i had to take them out too

but when i got to the bar, of course your gun disappears when you walk in - i partly solved it by throwing grenades down the stairs - the guy that stops you from going through the door by the bar then came up, and i took him out, then ran past the guy who normally says 'come in...' - becuase this time he was shooting at me - so i got through the door and into the rooms behind the bar - not much there, to be honest but you can go behind the bar and stand with Barkeep

shame, though, i couldn't shoot that really dodgy guy who keeps saying 'i have some information that could be of use to you stalker...'