45-70 is the brass use to form the T66 round. The neck needs to be annealed. Neck reduction is done in three steps. A 40 cal rifle die then a 33 Winchester die, then full length resize in 8x52R die. Bullet diameter is 0.323. Base diameter is 0.500 so cases listed above can not be used. The rim of 45-70 must also be reduced to between 0.552 to 0.558 in diameter. Also a bevel must be put on case head, outer edge of rim. Necks maybe too thick so a neck turner maybe needed to reduce neck thickness to about 0.012. If you want a form die set can be bought from CH4D or RCBS plus normal dies.