A more important one might be market saturation.
In terms of the symbolic importance of guns, the features of guns that make them dangerous for innocents makes them equalizers for innocents in the event of an assault. That merry go round of potentialities underlies the entire debate. So whenever there is a mass shooting, calls for the elimination of guns are matched with the desire to acquire them for defense.
The Navy Yard shooting and Sandy Hook, while both mass shootings, involved a different set of victims and their role in our culture. Sandy Hook involved children while the Navy Yard shooting involved the military. Never mind that guns are not commonly carried on military bases and certainly not in office buildings, any organization with the word "navy" in it calls to mind rough and ready soldiers kicking ass and taking names at the drop of a hat. The murder of defenseless children in what should be in a place as safe as their homes personalizes the experience for the public in a way that the killing of people associated with the military would not.
I expect a bunch of factors combine to make the Navy Yard shooting a less viable product for lobbyist group and firearm manufacturer profit. He used the wrong gun for the wrong reasons on the wrong people too soon after the last mass shooting and too late after landmark legislation had run its course. The result was outrage fatigue, legislation fatigue, stereotype confusion, and an event that does not fit the ideologically based business model of the outrage manufacturers and fearmongers that feed off of both sides of the issue.
= new reply since forum marked as read
