Abstract: A device is described with which a gas check can be squarely placed onto the shank of a cast bullet in a bullet sizing apparatus. The device is a gas check seating body with a laterally located slot so as to fit into the apparatus while partially enclosing a push rod below its head while resting on a shelf. The head of the push rod rests on the gas check seating body and supports an ejector rod located in the bore of the swaging die with an upper end so located that a gas check can be conveniently placed thereon. A bullet shank can then be forced into the gas check so it will squarely fit onto the bullet.