A leachable casting core and method of manufacture may include a plurality of legs configured to establish a plurality of internal flow channels of a cast component. Tie bars, with a first tie bar end and a second tie bar end opposite thereof, may couple to at least two of the plurality of legs. At least one of the tie bars may be oriented to form a linking cavity within the cast component between the internal flow channels. The linking cavity may serve as an obstruction to fluid communication through the linking cavity.