Arizona isn't the first to do this. Other states have already passed laws that forbid any state actor to provide any assistance to Feds who intend pursuing any federal law that is in violation of their state constitution.
The "usual suspects" for pro gun stuff like this are Flarduh, Texas and Tennessee. And they're joined at the hip. When one of them passes some new sort of pro-gun law -- like the 'Stand Your Ground law -- the other two will follow in short order. I might be wrong but I think all three already have laws forbidding assisting the Feds in any anti-gun stuff.
The big exception to "the big three" rule is Montana, which originated the "Firearms Freedom Act." The Montana FFA started because a gun guy in Montana (and state legislator) wanted to manufacture a juvenile-sized version of the old Remington 67 single shot .22LR bolt action rifle. These rifles were to be sold exclusively to Montana residents and with the understanding that the rifle was never to leave the state.
The federal gummint can and does use the Interstate Commerce Act whenever it feels like it the thwart state's 10th Amendment rights. But if nothing about the transaction ever goes across a state line then the ICA shouldn't kick in. So the Montana FFA specifically said we'll do whatever we want with our firearms so long as they are manufactured, sold and remain within our state.
To date, seven other states have passed their own version of the FFA. The Montana FFA genuinely was about being able to sell a gun that would live its entire life "locally," but the other seven states have jumped on the bandwagon to give themselves "standing' for eventually challenging Federal firearm laws as violations of the 10th Amendment. which all federal gun laws clearly are because there's nothing in the US Constitution that gives the federals the power to do jack shit about guns.
But like all such matters, nobody has yet thrown the first punch because that's a fight you don't dare start unless you have a strong chance to win, because losing it would set a precedent that would only make the problem worse.