Beagles brings up an interesting point - residence.
This is a legal term of art as is "domiciliary." It is often a grey area which is why I avoided it, but the grey area can be used to your advantage, of course. Whatever you do, keep your California residency as long as you have any guns in California, or as long as you might go back.
That means keep registered to vote in California (we need your vote, anyways), keep the CDL, and register and insure your car at your GF's place.
Once you are absolutely sure where you are going to stay, then and only then change your residency.
This is not to say that your "residency" is up to you, but what you do does count. It is a flexible concept, and it has to be. Think about it; if it takes 6 months to become a AZ resident, what happens after you leave CA? Are you a man without a state for 6 months? A tempting proposition, no doubt, but uncommon.