AP Photo

Given these last weeks, who doesn't know what an AR-15 is? Who hasn't seen the mind-boggling stats on the way assault rifles have flooded this country, or tabulations of accumulating Newtown-style mass killings, or noted that there are barely more gas stations nationwide than federally licensed firearms dealers, or heard the renewed debates over the Second Amendment, or been struck by the rapid shifts in public opinion on gun control, or checked out the disputes over how effective an assault-rifle ban was the last time around? Who doesn't know about the NRA's suggestion to weaponize schools, or about the price poor neighborhoods may be paying in gun deaths for the present expansive interpretation of the Second Amendment? Who hasn't seen the legions of stories about...