you can modify the bullet to allow seating further out..... noe makes a nice nose-sizing gadget that does that . it costs less than having a gunsmith re-throat your barrel.
or use a ” nose rider ” mold that has a nose that casts a sliding /engraving fit as cast .... nose diameter can be tweaked by varying the alloy .
myself i would choose a nose sizer; the noe has interchangeably sized inserts .
just some thoughts. keep us informed of your progress......somebody out there is bound to figure out these cast bullet sometime ...( g ) ...
ken