I don't think I mentioned shell holders for the formed brass. I use the same shell holder that the 40 S&W uses (I have the Lee universal shell holder set, so mine is a #19). RCBS lists only one shell holder for the OEM 8mm Nambu cartridge, their #25. RCBS lists nothing else for that shell holder, although I'm sure other cases might fit.
My formed 40 S&W cases don't fit in the RCBS #25 shell holder. Strangely, neither does Ed's OEM 8mm Nambu cartridge - the SH rim cut is too small. It does fit in the 40 S&W SH.
Lee's Universal SH set shows the 9mm Luger and 38ACP/Super Auto using the same SH as the 40 S&W [their #19].
Just a FYI...