I can't say for the .45/70 dies, but my Redding .308 die set is a three die set. One die is a FL sizer, one is a neck sizer and the 3rd is the bullet seating/ crimping die. They work pretty much like any other die set, but doesn't have the floating sleeve seater like the Hornady has. After you get the dies set up ( you did read the instructions that came with the dies, right? ) back the black stem out some and adjust it to seat your bullet. Don't set your die up to get a heavy crimp at first, as you'll play hob getting a bullet to seat. If you are loading cast bullets, you'll need an additional flaring die from RCBS or an "M" die from Lyman to properly flair the case mouth to accept cast bullets without shaving lead from them.
