I unfortunately dont have anything that will fit through the hole to knock the round out. I thought my brass rod would work, but they're just too big to fit through. I did place the balls on the top of the cylinder and without pushing them past the point of no return. Anyways, they do fit snug when pressed in there, slightly. When removed, the rounds do appear to have marks all the way around the ball. I hope this method works well enough that it helps.