In a small bowl, combine brown sugar, garlic powder, onion powder, and cayenne. Set aside.
Preheat the smoker to 225°F/107°C.
With the help of a sharp knife, carefully unwrap the bologna to remove the outer layer. Then with the knife score the bologna to create diamond shapes on all sides.
Spread the mustard all over the bologna, then season with the prepared seasoning.
Place the bologna on the smoker over indirect heat, and smoke for 3-4 hours or until the internal temp is 165°F/74°C and a nice bark is formed but not until it becomes black. During the last 30 minutes, brush with BBQ sauce.
Slice and serve in sandwiches.