You may recall early last week when we mentioned the pair of shootings at the Pentagon and the Marine museum at Quantico, Va., about 30 miles south. At the time, Pentagon officials thought the shootings “random” events but were studying “the possibility of a connection.” Today they connected them, after ballistics tests showed that both sets of bullets came from the same weapon. (There’s also a third shooting, which took place on Oct. 25 or 26 at the Marine Corps Recruiting Station in suburban Virginia, which also may have come from the same gun.) The FBI is on the case. The bad news: someone is shooting at Defense Department installations. The good news: the nut is apparently a loner, sort of the Lee Harvey Oswald of U.S. military infrastructure.