It's been a long time but I went through a black powder phase that included an Italian made Navy Arms .58 1863 Springfield copy. It would group .570" round balls into about 3" at 100 yards, but because of its authentic shallow 3 groove rifling, only with light charges, very tight fitting patches cut out of old jeans, and frequent cleaning. Round ball rifles typically have deeper grooves to grip the patches better so they can use heavier charges. Low power charges are fine for target shooting out to 100 yards and the extra work involved in loading patched balls is still a lot less trouble than casting mini balls. I'm afraid that if your first efforts at casting are mini balls you might give up casting before experiencing how trouble free and fast casting can be. By contrast, round balls are the easiest shape to cast.
If you're going to start with a mini ball mould, I would get an iron mold despite the cost. After pouring a mini ball you have to tap the mini ball out of one side of the blocks then tap it off the base plug then get the three pieces back together before they cool down or your mini ball skirts won't fill out. Adding to the difficulty, pure lead is the hardest bullet metal to make fill out and it will only do so if it's very hot. A flaw in a mini ball's skirt will blow out before the entire bullet clears the muzzel causing a flyer. Lee's aluminum mold parts cool off fast. For shape I'd just start with Lyman's modernized version of the civil war mini ball, the 575213 or 585213. Civil War soldiers used a pretty sloppy fitting mini so they could load fouled barrels fast but we're mostly concerned with groups on paper. I found that getting a close fit of mini ball diameter to groove diameter by changing from a 575213 to a 585213 improved accuracy a lot. I forget who sold them, but sizing dies for minis were available in .001" increments. The sizers came with a rod that had one end shaped to fit a 575213's hollow base. A mallet is used to tape the minis balls through the sizer nose first. I had a .582" sizer to match my .582" land diameter. The manufacturers of rifled muskets have not standardized a land diameter so I would measure yours before picking out a mould.
For starting equipment I'd get an iron pot from a yard sale or second hand store for casting over a Colman stove and a laddle with a pouring spout like the ones RCBS sells. Kitchen stoves that have a good exhaust fan also work well if your wife is agreeable. I was a long time hold out and stuck with old iron cooking pots and kettles for 20 years, long after my friends had all purchased Lee 10 pound bottom pour pots. 10 pound pots wouldn't heat lead fast enough to keep up with my casting rate using gang molds for handguns and I didn't want to put out the price for an RCBS 20 pounder. Eventually I inherited an RCBS 20 pound bottom pour, but the point is you don't need a lot to get started. A lead thermoter, a variety of molds, and a lubricator sizer for modern bullets should get priority over an electric pot, or at least thats the way I did things.
Good luck and be carefull,
Last edited by k22fan; 03-24-2011 at 11:48 PM.