About 18 to 20gr of real Black Powder or Pyrodex ought to be a good start for the balls. I doubt you will get any benefit from Minie bullets, tried them myself & found the balls to be just as accurate with less recoil. Bullets had similar sized groups a few inches higher Primers - try CCI #10 / #11 or Dynamit Nobel No. 1075 - depends on the nipples to what fits best, may be too small or too big.