The NRA feels that the authority lies with the Bureau of Alcohol, Tobacco, and Firearms (ATF). However, a legal expert for the ATF, Rick Vasquez, has already deemed the issue legal from their standpoint. You see, a bump stock does not make a gun “fully automatic” in the eyes of the technical expert. Therefore, it cannot be considered an illegal gun.
Others believe that Congress should be more explicit with their automatic weapons ban and include technologies that can convert semi-automatic weapons to fully automatic weapons just like the bump stock. This would be a more inclusive piece of legislation that recognizes how conversions can increase the lethality of a mass shooting.
Either way, it seems that we can all agree that bump stocks are a tool that make something legal, into something illegal and more lethal. And on that note, it seems that because a bump stock is not a gun, its manufacturers can be sued for loses attributed to its sale (third party injury is usually protected when it comes to gun manufacturers, by the 2005 Protection of Lawful Commerce in Arms Act).
Of course, this may limit the lethality of mass shootings, but it still does not get to the ROOT cause. What actually caused this man to walk into a hotel, perch up on the 32nd floor, and indiscriminately shoot concert-goers? Proactive solutions will always be more effective than reactive solutions, but those solutions are difficult when the man appears to have no motive other than some perverse thrill he wanted to give himself upon his Earthly Exit.