I picked up a Lyman M die for the 405win (7342387), works beautifully with the 450/400 case. Expander in it was a .410-.412, which happened to be just what I wanted for the LBT bullets. Saves disassembling the Hornady seater die to put the Lyman M style expander into it to do the cases with. In talking with Hornady, the slip collar for the 450/400NE 3" die is the same one as the 405win, with a .415 dia. crimper in it. They will supply custom expanders or different sized collars for the sizing die & seating die, special order. 800-338-3220 ext 261, Ben Syring. And of course the Buffalo Arms custom expanders will fit the M-die or can be installed in the Hornady seater die.I think the BAC custom expanders come from C&H, so they can likely be ordered there also. I think perhaps if I had this to do all over again I might go to C&H for the complete die set, they will set up the dies for whatever combos you want, all from one place, about a 200.00 touch though.