FWIW I will be huntng cow this year with my Traditions TN (its super short and will fit well on My Mnt Bike rack and in the blind). Will use a "Ballette" (kinda close to a .54 in weight). My TN is a 32 twist as well, a rare bird. Have had no luck finding a 66 twist barrel and have not shot RB in it. I personally prefer PRB.
As for soft or hard, if you can shoot you'll do well with soft lead in the boiler room. If you think ya might ia shoulder I still say soft. Pop shot his yearling buff with a soft conical and it blew through a shoulder, destroyed the lungs and we recovered on the far side underskin. I'd say a yearling Buff about like a big Bull elk in bone density?
As for soft or hard, if you can shoot you'll do well with soft lead in the boiler room. If you think ya might ia shoulder I still say soft. Pop shot his yearling buff with a soft conical and it blew through a shoulder, destroyed the lungs and we recovered on the far side underskin. I'd say a yearling Buff about like a big Bull elk in bone density?