In the case of Alexis I still say his gun purchase was not proper-—even before he might have been a head case. He could not have purchased, even a long gun, in my state at least, because he could not have proved residency. He was living in a MOTEL. His NIX background check would have asked for his permanent address and he didn’t have one yet. And his Navy ID card would not have had an address on it. His drivers license reportedly was current but from Texas. We’re not getting the whole story regarding the shotgun purchase which means there’s more than one nut-case involved in the story.
You can buy long guns across state lines. For now. It’s handguns that must go FFL to FFL.
Whatever address was on his drivers lic had to match the one he put on the 4474 form, and that’s all.
I bought a shotgun in Nevada like that, and a rifle in some other state.