Does anyone know where I could find a shell holder converter for an old Herter's #3 cast iron press so I can use RCBS shell holders? I was told by a guy at a gun show that they exist. He said he has the same press and also has the converter. He told me that he thought he bought it at Cabela's years back...but I called Cabela's and they didn't have anything like that and didn't know where to send me looking. Any clues or tips are appreciated.