[demion]

Which weapon detection systems are common? Metal detector, gun powder/explosives detector, x-ray scanning,... ?

And how often in the normal street life do they appear?

[Jayde Moon]

Start at where they appear in our time.

Liberally layer them into AAA Communities, Neighborhoods, and Districts.

Put a bunch in AAs and several in As.

Sprinkle some into Bs and a dash into Cs.

[witchdoctor]

Not that I'm paranoid or anything but I regularly have a drone with me that has a Magnetic Anomoly Detector, just saying. Those things are dirt cheap as far as frequency the real question is how concerned is the owner of the place you're going to about weapons? The more concerned they are the most detectors I would put.