I use a .530 roundball, .018 patch lubed with Ballistol and 80 grains of fffg goex powder in my Investarms made Trade rifle with excellent accuracy. The maxiball is made oversize to engage the rifling as you load it, I have never tried them in mine. The rifling is much too deep for a minie ball to expand and properly seal the bore. The above load works great in mine, you may have to do a little experimenting ti find your best load, good luck!