While there are rules for giving those SINless shadowrunners fake paperwork to wave at the nice Lone Star officer to prove it's perfectly OK they're toting around Wired Reflexes III and an assault rifle, it's not clear what (if any) requirements there are for characters to get restricted gear under a legitimate SIN, either if they have the SINner quality or you're playing a legit characters campaign. If somebody wanted to have a legal pistol or PI license, how would you cost it for them? Charge money, require them to get a Quality, just let them claim it as part of their identity?
I'm assuming legitimate gear would be easy to track obviously (being directly linked to your ID), and maybe you'd have to broadcast it in high security zones (either from your commlink or possibly directly from the item in question; I can see the wireless in weapons being used to send out your permit info to law enforcement as you walk around a AAA neighborhood), but can you think of any other in-game limitations that might apply? I presume generally loose permits given at least one megacorp would gleefully push to make it easy, and of course violent crime levels being rather high; I seem to recall one old reference saying a substantial portion of people in Seattle owned guns thanks to all the gangers and whatnot. Or, come to think of it, with some of the nasty critters out there having a machine gun might actually be vital to wilderness survival.
And on a side note that applies to legal and illegal permits, how broadly do you allow permits to be defined? I've seen sample characters where their permits are listed specific to each weapon; do you do it that way, or is it possible to have a generic pistol/rifle/etc. permit like modern US gun laws? Or just have a generic "gun" permit, for that matter.