Metal heads are in mourning.  Reports are circulating that guitarist K.K. Downing has officially retired from heavy metal band Judas Priest.  Reports say he will not be joining the band on its upcoming "Epitaph" tour, which is the legendary band's final global trek. Downing, 59, will be replaced by 31-year-old British guitarist Richie Faulkner on the bands last tour.  K.K. Dowling … you’ve got another thing coming!