The unfolding scandal over a gunrunning investigation allegedly botched by the Bureau of Alcohol, Tobacco, Firearms and Explosives could do what years of criticism of the long-beleaguered agency never quite accomplished — result in its demise. That, at least, is the view of some former ATF employees and advocates on both sides of the gun control debate who have watched the agency struggle to contain the damage from an operation intended to trace the traffic of illegal guns to Mexico that has reignited the harsh criticism often directed at the ATF in the past. The agency, which moved from the...