GZS probably has some sort of scanner that does a little more than just scan your body, so just not having the gun on your person most likely isn't going to work.
 
You get the idea that the machine is probably not going to scan the ceiling though, so you get out your duct tape and fix it to the pistol, you then climb on top of the automatic teller and jump up to stick the pistol on the ceiling. You end up falling on your ass, but you succeed. You then press some buttons on the machine, where it proceeds to ask your name and how you're going to pay. You type in your name and insert you debit card where upon it drains most of your account. The door you stepped through sudden shuts and a hum is heard. You take a deep breath and hope for the best.

"Now scanning for unauthorized items…Scanning…Scanning…Scanning complete. You have been allowed entry, the elevator doors will now open, your room number is 23, thank you for choosing Ground Zero Survival!" an  emotionless electronic voice remarks as the elevator doors open. It worked!

You quickly climb back up on to the teller and jump up to grab your pistol, (this time able to maintain your balance better) toss it into the elevator opening and then rush in with all your belongings and take the long elevator trip down.

When you get to bottom the elevator door opens to large sterile hallway with lines of other closed metal doors on either side As soon as you enter, the elevator doors slam shut and you hear it going back up, you also notice there aren't any buttons to call it back…before you're able to worry about that little detail you're met by a few of your new neighbors. One is some tall skinny guy another is a brunette woman who begins talking to you.

"Hey, another new neighbor! My name is Nina and this is Ron, what's your name?"

She is entirely too fucking friendly given the situation.

"Why aren't there call buttons back on the elevator?" you ask ignoring her question.
"Huh? Oh I guess it's a safety feature. The elevator automatically goes back up so the other people can get in as quickly as possible. Ron suggested that they might've thought someone would deliberately try to keep the elevator down here to prevent anyone else from seeking shelter. Though I can't honestly imagine that anyone would do such a horrible thing."
"Been living on earth long Nina?" you ask rhetorically. "Great, so I'm basically trapped down here due to the brilliant engineering minds of GZS…so is it just us so far or are their other people here too?"
"There are a few others, if you come with us we can introduce you to…"
"Maybe later, look we're gonna be stuck down here for a long time so I'll get to know everyone soon enough, right now I just want to go to my room and rest."
"Erm, okay…" Ron says as you push past them both.

You head to your room which is equipped with the basic requirements; food and water dispenser, shower, bed, and a cabinet. (You hide your pistol in your mattress) There's a standard Shelter Operations Manual sitting on the table as well as a Shelter Booklet about socialization, rules, guidelines and such, both of which you skim through every now and then. There's a big public recreation area and a couple of other public rooms where your neighbors gather, but you stay in your room and keep to yourself for the most part. Sometimes in the middle of the night when nobody else is around you'll watch the TV in the living area to keep up on current events.

You hear other people arriving over the month. Ron and Nina greet them all, you can tell those two are going to be the ones to "organize" shit and probably try to decide what's "best" for everyone. Always saying stuff that they read in the booklet.

"Fucking busy bodies…" you say as you fall asleep watching the world in its death throes on TV…

Monday 8:00 AM

"…BEEEEEEEEEEEEEE…"

You groggily wake up and see a test pattern on TV.

This is it.

You feel a small tremor and then you turn off the TV, just as Nina and Ron come walking in.

"What was that?" Nina asks.
"Test pattern, I think Armageddon arrived." You answer.
"What?! I can't believe it!" Ron exclaims.
"Why are you so surprised? I mean that was the whole point of coming down here right?"
"Yeah, but I dunno…I just wasn't prepared for it actually happening."
"Christ, Ron I've overheard you say you were the first one in this goddamn shelter, you of all people should've long gotten used to the idea of living down here."
"What is your problem? You been nothing but hostile since you've got here!" Nina exclaims.
"My problem is I'm stuck down here with a bunch of people I don't really know and if you two are any indication I don't want to know."
"How did you even qualify to get a room down here?"
"Good clean living I guess, so is there supposed to be something special we do now?"
"Uh, yeah I think so, it mentions something in the booklet I was reading that came with the shelter, we're supposed to gather everyone and tell them."
"Okay well I guess you guys go do that then. I'm just going to check on something here."
"Okay, but we're supposed to have some sort of vote to decide on how this place is going to be run, if you don't show up you don't get a vote." Ron reminds you.
"I know Ron, I've read the booklet." You answer unenthusiastically.

Ron and Nina leave you and go tell the others of the situation and follow other things it states in the booklet. You're wondering if you should even stay down here. All these people seem completely different than you. You wish there was someway to call the elevator back down, but after checking a GZS computer it states that it won't come back until it detects that the surface is safe for habitation again…which basically means not in your lifetime.

It's probably just as well since the surface probably isn't the safest place you'd want to be, lord knows what the hell it looks like now, not to mention the radiation factor. Then again you'd still like the option to leave if you wanted to. You go back to your room, read and enjoy the solitude until Nina comes to get you.

"Hey! You didn't show up for the meeting! We're discussing which ways this place could be run, are you coming or what?"

You be obstinate

"I don't feel like going anywhere, you guys do what you want." You say, but Nina insists on invading your space.
"Hey look, I know you don't wanna do shit, but unfortunately we're in a real deadlock and we could really use your vote to break a tie."
"HEY! I told you I'm not going anywhere, now get the hell out of my room and stop invading my privacy, unless you're looking to get invaded by me."

Nina is offended by that remark and starts to hit you. It doesn't really hurt, but it's annoying and stings enough for you to start blocking her.

"How dare you say something like that to me!"
"Stop it! Get outta here before I throw you out, you crazy bitch!"

While you begin to get up to avoid her slaps, your shift on the mattress causes your pistol to fall out on to the floor, Nina notices, stops hitting you and backs off.

"Oh my god is that a gun?!"
"Well, uh…yeah." You say picking it up.

Nina suddenly runs off thinking her life is in danger, you soon here her yelling "Help!" and similar cries. You immediately go chasing after her, in an attempt to reassure her that you're not some murderer.

You see her run into the conference room and follow, when you arrive, a leg trips you up as soon as you enter causing you to slam face first on the floor. Then somebody tries to take the gun away from you, its Elliot.

You feel a hefty boot kick you in ribs and knock the wind out of you, and a couple of other people start dog piling on top of you. Nina is ranting to everyone saying you tried to kill her. The fact that you came running in here with a gun, doesn't exactly persuade them from thinking differently. Meanwhile you lose grip of the gun and Elliot takes it from you, but "accidentally" shoots you in the face with it.

"Oh my god! I didn't mean to kill him! He wouldn't let go of it!" are the last words you hear.