By Steve Holland and Brad Brooks WASHINGTON/UVALDE, Texas (Reuters) -A day after promising residents of Uvalde, Texas, action to address gun violence, U.S. President Joe Biden on Monday sought to appeal to “rational” Republicans to curb high-caliber weapons and take other federal action to prevent more mass shootings. “Things have gotten so bad that everybody is getting more rational about it,” Biden said as he returned from his weekend trip to memorialize the 19 children and two teachers killed last week in the nation’s worst mass school shooting in a decade. “The idea of these high-caliber w…