I am one of the very few who may and have legally purchased guns in two different states and that includes here in CA where the rules are tough.
I have a CA REAL ID and a NV Driver's License and Nevada CCW. I am a legal resident of each state. I meet every requirement to buy a gun in either state under both federal and state laws.
In fact, this is the only legal way I can keep a gun in this state when I am in NV, by federal as well as CA law. Or else, I would have to travel between states with the guns in my possession.
And I have, several times, purchased firearms in each states. I am a collector as well as a shooter. I am mostly into 5.7 by 28 MM stuff, and I own every model of gun there is in that caliber that is legal to own. PS-90, FN FiveseveN (both colors), AR57, Masterpiece Arms 57, Ruger 57, CMMG 57 (pistol and rifle) and a few others. I even have a custom made barrel in 5.7 by 28mm for my Thomson Contender. And I have many other calibers, mostly in NV, as most of my firearms are not even legal here in CA.
I put in a binary trigger in my CMMG (also illegal here in CA of course, but not in NV). And I can covert it to 22LR and back to 5.7 in seconds, as the same barrel can be used as 5.7mm is very close to .22 cal. 22LR is a lot cheaper to fire!
I put this rifle together from the parts, including the lower receiver trigger assembly, for the binary trigger.
This is me firing my CMMG 57 rifle converted to .22LR (and is binary in either) at the Carson City Outdoor Range for just a few seconds. About as fast as a full automatic, but perfectly legal (in Nevada).
-Don- Auburn, CA