I thought it might be a venting issue, also. Some other molds I have from grandpas collection were unvented at the collars and a little work with a needle file had them working in no time. That said, if you look at the pic, this one is well vented right at the point it needs to be. I also took my little needle file to the other side which you don't see. Both sides are vented now on two of the cavities. I was working with the 1/2 oz. as usually if I have any problems it will be with the smaller sizes. That and was only wanting to pour the 1/2 and 3/8 cavities anyway. Thanks for the replies, fellas.