Lived in Illinois for a while, then moved to Arkansas. I milled around for a week of so, then decided to buy another gun so got an in-state drivers license and went and bought one. No delay, no arrest.
Anyway, what my point was is that NICS didn't say "Holy $hit, he's from out of state!! Call the police" Instead I had no delays and walked out with a purdy AR-15. Also about 6 months ago a friend of mine came down from ILL to visit. We went to the gun store and he wanted to buy a gun. He went to the counter, yellow formed it with his real address and used his ILL drivers license. Shop called NICS and he was approved. We went and shot and then he took it back home with him.
NICS uses your SS# to check the FBI's list of felons, not with the IRS for where you live. And David, I don't know who broke the stick off in your ass, but your SS# is even optional on the yellow form. If you don't want to put it on there you don't have to. It's almost a guaranteed delay, but what the hell, can't have everything.
Ice, I can't speak for AZ, but when I moved down here I gave them IIRC $27 and traded liceses. No written test, no drivers test, no eye test, and no temporary license. Walked in with IL license, took about 15 minutes in line and to get a new mug shot, then out the door with my permanent AR license. Real easy, then next day bought a gun. Again, the AZ/CA situation could be a lot different, but NICS doesn't give a crap.