Preheat oven to 425 degrees F. In a large bowl mix together dry ingredients. Add buttermilk, incorporating it into the dry ingredients with a fork. Using hands work dough briefly until it just comes together. Turn dough out onto a barely floured surface and knead until dough becomes 1 piece and is slightly sticky, no more than a minute. Roll or pat dough into a round approximately 1/2 inch thick. Using a 3-inch biscuit cutter cut rounds. Re-roll scraps and continue cutting rounds until all the dough is used. Place each round on an ungreased baking sheet about 2 inches apart. With a pastry brush paint the top of each round with melted butter. Bake for 12 to 15 minutes or until lightly browned.