Before the brief and almost certainly unfruitful discussion that we will have about gun control in the wake of the shooting at the Washington Navy Yard, there is one task that must be completed: determining exactly which guns we’re talking about. In the fog of tragedy, with the investigation only just beginning and the memories of the twelve people killed, apparently by Aaron Alexis, still new, this is not such an easy thing to do.

Initial reports suggested that Alexis brought multiple weapons with him into the Navy Yard, including an AR-15, a semi-automatic rifle related to the military’s M16. The reports, it appears now, were not true: according to the latest information, Alexis, when he was killed, had not an AR-15 on him but a shotgun and either one or two handguns. And it may be that he started with only the shotgun; there are reports that he took a handgun or handguns from security guards at the Navy Yard.

If this latest version of events is true, there will likely be even less of a discussion of gun laws—or the lack thereof—and how they might have applied to Alexis. It appears that he bought his shotgun legally—reportedly last week, in Virginia. He was allowed to buy a firearm despite having apparently struggled with mental illness, and despite his involvement in some disturbing gun-related incidents, because he did not have any felony convictions, and because the bar for keeping someone from buying a gun due to mental illness is extremely high.

If there is anything significant in how Alexis and the weapons he carried may shape the debate about gun control, it may be in the still-unresolved question of where he bought his shotgun. Even after the landmark District of Columbia v. Heller case, in which the Supreme Court struck down D.C.’s handgun ban, the District still has some tough gun laws on the books. Alexis would likely have been able to obtain the shotgun there legally, but D.C. makes the process of buying a weapon difficult and time-consuming; the gun laws in Virginia, in contrast, are comparatively lax, and would have allowed Alexis to buy the gun more easily and quickly. It is situations like this that so concern the pro-gun-control mayors of America’s big cities. They may have strong laws inside their boundaries, and they may enforce them, but it’s impossible to stop the flow of weapons coming in from more weapon-friendly jurisdictions.

There is also the question of how something like this could happen inside a military facility, where the presumably armed personnel represent the very definition of the “good guy with a gun” invoked by N.R.A. Executive Director Wayne LaPierre as the solution to gun violence. Some conservatives are starting to argue that the problem at the Navy Yard was actually that there weren’t enough guns present—that Democrats have turned military bases into “gun-free zones” where even trained combat veterans are vulnerable to lone madmen. This argument first came up after the shooting at Fort Hood in 2009, but it is misguided, as it was then. The suggestion that it is Democrats, and specifically former President Bill Clinton, who are responsible for keeping guns off bases comes from a series of thinly sourced articles about what happened at Fort Hood, and is based on an Army regulation issued in 1993, during the Clinton Administration. That regulation was intended to put into action a Department of Defense directive from 1992, during the George H. W. Bush Administration, and versions of that directive had been in place for years by then. In fact, the government was merely implementing a law originally passed in the nineteen-fifties that allows for some members of the military to carry guns for security purposes. Unfortunately, in this case, that law doesn’t appear to have made a difference.

Photograph by Jacquelyn Martin/AP.