One more option for more extreme enlargement of the driving bands in a mold would be to visit this site initially designed to convert steel moulds into hollow point moulds but he has expanded his services to include this service. I know folks who have used him and are extremely happy with his work. It costs a little bit but is less than buying a custom mould for sure. His e-mail contact is
erik@hollowpointmold.com or google up hollowpoint mold service. You can get replacement hollow point handles and pins for Lyman/Ideal molds and lots of repairs, modifications done here. Recommend to add to your favorites list for sure if you are a casting junkie like me ,,, 10 Spot