Chalk the federal ban on interstate gun sales up as another example of problems with the 17th Amendment. In other words, I suspect that the Senate would have killed the gun ban bill if state lawmakers still uniquely controlled the Senate.
Try not to misunderstate what the problem was/is. The 1968 GCA allowed adjacent interstate sales of long guns but required that handguns be purchased by non-licensees in their state of residency. This ruling just knocks out the difference between long and hand-gun. So far I can’t tell if it knocks out the contiguous state provision. In either case it’s a large deal.