On Sunday, the country marked 100 days since a man wielding a semiautomatic Bushmaster assault rifle killed 20 young children and 6 faculty members at Sandy Hook Elementary School in Newtown, Conn. Just days earlier, on March 19, Senate Majority Leader Harry Reid, D-Nev., announced that he would not include a ban on military-style assault weapons - like the rifle used by the killer at Sandy Hook - in the Senate's upcoming gun bill and would focus instead on other gun laws that stood a better chance of passage. Disappointed supporters of the ban mostly moved on, fixing their sights...