In the method of forming a hollow metallic golf club head having wall structure defining a front wall, a heel, a toe, a rear wall, a sole, and a top wall, the steps that include providing a wax shell covered pre-formed core body, the thickness of the wax shell corresponding to the desired thickness of the wall structure, forming a ceramic shell about the wax shell; removing the wax shell by melting the wax, thereby to form an opened gap between the ceramic shell and the core body, and casting molten metal into the opened gap, thereby to form the wall structure extending about the core body and at the sole, while forming and maintaining port structure through the wall structure and spaced from the sole, and allowing the wall structure to solidify to form the head; removing the ceramic shell from the wall structure, and removing the core body from the interior of the solidified head, and via the port structure.