This hydroform cartridge die has been developed around Lapua “blue box” brass but the dies can be used with other brands of brass.
The expander pin diameter is 0.242”. The outside diameter of a hydroformed case will be 0.271” to 0.272” depending on the brass. The hydroform die will expand the case neck and reshape the 6mm BR case to the 6mm BRA profile.
Annealing of the hydroformed cases is recommended before loading.