Vast experience on Shiloh board.
https://shilohrifle.com/forums/
I buy most of my cast .38-55 and .40-65 bullets from Montana Bullet Works.
https://www.montanabulletworks.com
Get dies and load your own, even with nitro.
ETA. Jacketed bullets won't hurt the barrel, it will just be a cleaning chore to get the copper out for best accuracy from cast. Badger recommended break in with jacketed.