Force the end of horseshoe back into the ring with your anvil or mandrel. This will increase the metal for the ring, increasing its diameter to more than the original slit hole. Continue forging the ring until it is round and uniform but not too thin. You will be aiming for a ring size of approximately 1¼ inches internal diameter and 1?8 to ¼ inch thickness. Chamfer the edges by holding the horseshoe on an angle, so the inside corner is in contact with the mandrel and hammer the opposite corner. Rotate around the ring using light, overlapping hammer strokes to get a smooth finish.