Preheat oven to 400º. Grease 8-inch round baking pan. In large bowl, combine flour, oats, brown sugar, baking powder, and salt. Cut butter into flour mixture using pastry blender. Dough will be lumpy. Fold in raisins. In small bowl combine buttermilk and egg and beat until well blended. Add to flour mixture and stir until well blended. With floured hands, pat dough into prepared pan. Using sharp floured knife, deep score top of dough forming 8 wedges. Bake 20-22 minutes or until golden brown, scones should spring back when pressed lightly on top. Remove from oven and cool in baking pan for 10 minutes. Remove from pan and cool on rack. Dust with powdered sugar. Serve warm.