its not illegal to sell firearms. Its illegal to have them not registered to the new owners. Maybe be a holding period between the legal sale of handguns. some long guns can sneak under registered with a bill of sale. say you buy hunting gun off friend, It really dont need to be registered if your a true gun owner and keep the bill of sale.
Registration is not required in most States. I have guns I've bought second hand with no paper work at all. The cops just want to see is if it's been reported stolen if they find it in your car. OP is from Arizona which I believe has fairly lax gun laws like Louisiana.
I have a large former Aircraft Carrier for sale - should suit an American with a paranoid fear about 5 year old trespassers in their garden.
$20...slightly used ...smells like hot summer night ass mixed with a bit of dirty nutsack contact Orison319 for shipping info
I have a Hi-Point sub compact 9mm, 2 magazines, a holster, a firesafe for it, and 200+ rounds of ammo that I need to sell. $200.