Were these sold as complete guns or pieced together?
If it's new in box then it came with a muzzleloader barrel.
Encores came with muzzleloader rifle barrels or centerfire rifle barrels. Because the frame can use centerfire rifle barrels the muzzleloader gun is subject to a NICS check when sold by a dealer.
Later on TC made a dedicated muzzleloader on the Encore frame. The centerfire barrels will not fit this gun: No NICS check required.