Your combo came with the Tracker II 12ga. It has open sights and is not drilled for a scope base. None of the "standard" weight 12ga barrels come D & T'd for a scope base. The chamber wall is not thick enough for the drill and tap to be safe, by H&R standards. You may find a gunsmith who will do it, but most will not. If you want one from the factory that is drilled and tapped it will have to be the 12ga ultra barrel as it starts out as a 10ga barrel and the chamber wall is thicker. Sorry, that's just the way it is.
cookiemann