Sand casting and semi-permanent mold casting are generally more complex than die castings where design features have to be compatible with the opening and closing of dies in the horizontal direction. This does not have to be the case if salt cores are used.
Salt cores are made as die castings and these die cast salt cores are then placed in another die cast machine and another die casting is made that contains the salt core. The salt cores are then washed out and the resulting die casting has features that reverse engineering by competitors can not decipher.