Bushmaster—the gun manufacturer of the rifle used in the Newtown, Conn., shootings—is being sold by its owner, the private equity firm Cerberus Capital Management. Cerberus acquired Bushmaster in 2006 and merged it with other gun companies to form the large and lucrative firearms manufacturer Freedom Group. But, having noted in a press release that “it is apparent that the Sandy Hook tragedy was a watershed event that has raised the national debate on gun control to an unprecedented level,” Cerberus is getting rid of its gun assets. This could be the first in a trend …