Can't help you much on the seating plug (I use flat points and hollowpoints, may just have to drill it so it works with any bullet) but I can tell you there is probably no need for a different crimping die. I have used the RCBS dies for my 45-70's for about 15 years with excellent accuracy. If you aren't happy with your results, try Hornady 300gr. XTP's over Reloder-7. I have had great results using this combo from 41 grains of powder in a Handi to 50.2 grains in my Browning High Wall. As usual, these loads have worked in my guns, be careful with yours. Those are published loads, though I don't think I would go so far as 50.2 grains in a Handi, for safety reasons and the wake-up-call recoil. BTW, the 41 gr. load drops deer really dead.