or emplaced weapons akin to the E-Web turret of Star Wars fame

Basically, a heavy bolter. They are supposed to be a crew-served weapon, after all, even though particularly buff individuals or warriors in powered armour can lug them around solo.

You could even come up with an automated "sentry turret" version a la Alien 2 by fitting it with a servo mount and connecting one or two of these babies to a Servitor who acts as their guidance system. A pale cyberzombie with wires connecting their head to a bunch of stationary guns should make for a suitably grimdark image that fits right in with a horror campaign.

Also, this kind of setup easily allows you to control the scene -- the guns may work nicely keeping the 'stealers off for a bit, but they only need to take out the Servitor to silence the turrets .. oh, is that an air duct above the Servitor's head?

@ SgtLazarus

I do want to make them very paranoid, especially towards any "friendlies". As mentioned before, having genestealers hide among a crowd of survivors and then pop out and surprise them, birthday cake style, would make them poop their pants and question who they can trust. I want them to feel like they are never safe.

@ L ynata

I like the idea of a gun servitor of sorts. Im sure they still have some guts that aren't metal and will make for a nice and juicy kill.

I didn't want to reference any of the Heavy Weapons in Only War because of the tendency of Heavy Gunners to carry them everywhere, but in essence, yes. Though I'd go so far as to say that you probably want a Heavy Stubber if you're worried about depressurising / flooding the city as a factor. Vehicle weapons can be used as emplaced turrets that manpower can't lift, so maybe an Inferno Cannon position would work on that front. Set up similar to the rebel turrets on Hoth. Also double up on the horror as the Genestealers just rush through the flames, making all their agility tests.

If you want the paranoia of friendlies to set in, I recommend that you have NPCs around the area, and occasionally have some that were previously friendly and helpful turn on them. Eventually they'll start to question who's trustworthy and who's a traitor.

I think I have just about everything I need and honestly dont know what else I could ask. Anyway, thank you all for the help.

I think I have just about everything I need and honestly dont know what else I could ask. Anyway, thank you all for the help.

No problem.

Be sure to tell us how it went

I shall. May be a while. Was planning on doing it this weekend, but I ended up doing beta testing for a mod. Oh well.