Preheat the grill to medium-high heat, about 400˚F.
Pat the chicken legs dry with paper towels. Rub the chicken legs with olive oil and add to a large bowl. Add Head Country Championship Seasoning and toss to coat well.
Place the chicken legs on the grill and cook for about 20 minutes, turning them every 5 minutes. Close the lid between flipping the legs.
Brush the chicken legs with Sweet Mustard BBQ sauce and continue to cook for an additional 15 to 20 minutes. Flip the chicken 2 to 3 times as they cooking, brushing with more BBQ sauce each time.
Remove from the grill once the internal temperature reaches 160˚F to 165˚F. Let rest for 5 minutes before serving with additional BBQ sauce.