A coring system for producing a flash-free one-piece die-cast body for an electrical connector. The electrical connector of produced by the coring system of the present invention may be used for securing two electrical cables to an electrical panel or electrical box through a single knockout hole. The coring system includes a first core, a second core, and a connecting arrangement for connecting the first and second cores in such a manner that there are no gaps between the joined portions of the two cores. When the cores of the coring system are joined together by the connecting arrangement and placed in a mold, molten metal may be introduced to the mold at the joined area of the two core pieces to form a one-piece flash-free connector body according to the present invention.