WASHINGTON (Reuters) - Flags are lowered, sorrowful statements are issued, pleas to lawmakers are made, again. In the wake of two mass shootings in California this week, President Joe Biden has followed a heartfelt and familiar script of outrage and grief over gun violence in America, coupled with a renewed call for Congress to pass legislation banning assault-style weapons. Such a ban has little chance of passing the Republican-controlled House of Representatives or the Senate, which is narrowly controlled by Democrats, political experts say. But Biden's stubborn strategy continues: make a ban the focus of public discourse whenever a mass...