Lyman has addressed this subject ,they are sending me a book on how it can be done with certain alloys you can make yourself and cast with your existing equipment ,but it isn't fool proof and to be correct i needed to buy this book.
They said the Spanish have done a flashing process for years that works and Lyman on a special order can supply the dies needed as bullet Dia .becomes an issue if you still use lead.
It has surfaced again because of all the lead free Laws going into effect on some ranges , the plus in this is it also allows you to make bullets suitable for use in a gas system.
Your velocity's will suffer some though ,and to make pure lead free bullets you will need to buy some things.
They emailed me a list of places to get the book ,so i ordered it and when it comes in i will post it for you guys.