You can easily increase the weight fo the .58 minnies by turning the plunger down and shortening the hole it makes in the end of the minnie bullet - all the way to solid is expansino isn't needed, or it fits well in a .58 bore. With heavier charges or the faster burning powders & if of pure lead, the solid .58's will slug up to fill the grooves (if any) of the barrel. Also, since they fit the sabot in that situation, they do not obtruate and get out of balance as could happen with thin skirts.