Firearms makers sold off for a second day as institutional investors and retailers responded to concerns raised by last week's mass murder of grade schoolers and teachers in Newtown, Conn. Sturm Ruger (RGR) dropped 8%, putting shares down 11% so far in what could become a third straight weekly decline. Smith & Wesson (SWHC) gapped down to a 10% loss, off 15% so far for the week. Both dropped amid very heavy selling and are now well below their