Place the drumsticks in a large bowl and pour the buttermilk over them. Turn the pieces so each one is fully coated, then cover and refrigerate for at least two hours.
In a separate bowl, combine the flour, smoked paprika, cayenne pepper, garlic powder, salt, and black pepper. Stir until the spices are evenly distributed.
Remove the drumsticks from the buttermilk, letting excess liquid drip off. Dredge each piece in the flour mixture, pressing lightly so the coating sticks well on all sides.
Heat vegetable oil in a deep skillet or pot to 350 degrees. Fry the drumsticks in batches, turning occasionally, until the coating is dark and crisp and the internal temperature reaches 165 degrees.
Drain the cooked drumsticks on a wire rack set over a baking sheet. Sprinkle with chopped parsley just before serving.