The Las Vegas shooter had multiple rifles fitted with the attachments.

Team Trump may be walking back most of the rest of what Trump opined we should be doing about gun violence, since that White House meeting in which he opined a great many things. But the would-be ban on "bump stocks," currently legal devices that allow semiautomatic rifles to be fired at nearly the same rate as illegal automatic versions, appears to be a sacrificial action they're still willing to take.

And so the Bureau of Alcohol, Tobacco, Firearms and Explosives is scurrying to re-examine the issue and reverse their previous conclusions.

Officials in the bureau’s press office appeared surprised when first asked about the president’s comments and said the agency was still determining whether it could ban the devices — which it had previously said it could not do. Mr. Trump’s remarks had the desired effect. The Justice Department and A.T.F. aligned themselves with the president, backing away from the bureau’s earlier conclusion and announcing on Saturday that the agency can ban bump stocks under current law, as the president had promised. On Monday, Attorney General Jeff Sessions reiterated that he had sent a draft proposal to effectively ban bump stocks to the Office of Management and Budget, which approves federal rule changes.

As usual for this administration, this is a bit of a mess. The ATF previously found that they could not, in fact, regulate the devices because they were weapon "attachments," not actual weapons. Trump and Sessions are asking the ATF to reverse that legal conclusion and replace it with another. If that happens, there will be lawsuits galore and the NRA will be at the front of all of them, insisting that being able to alter a weapon so that is shoots as many rounds per second as you want it to is a God-given right and necessary to protect fine American would-be terrorists from whoever the voices in their heads are telling them to kill.

The way around all of this would be for Congress to pass a new bill banning the devices, but it's not clear that Republicans are willing to stomach even that much. So Team Trump will be doing this—at least for now. There's a good possibility that the ATF will review their decision and again find they cannot take action without new law, in which case we'll be right back where we started.