The factory 45-70 brass for Hornadys FTX loads are shorter than normal anyway, aren't they? That'll make reloading more challenging, won't it? I always preferred RCBS 458 405 gr mould for 45-70, my understanding is that it was designed specifically for Marlins 45-70, and it certainly feeds like it was. I also used RCBS 458 425 gr FN U bullet for a lighter load. My first cast bullet deer was collected with this bullet. With my 458 SOCOM I now use RCBS 458 300 gr GC design for a light bullet, and Accurates 46-525VG for a heavy from a borrowed mould.