WVS:
I cast about 2,000 minies a year for use in N-SSA competitions, where guys with rifles much like yours get excellent performance.
First, the most basic rule for minies: Use only pure, soft lead. The beauty of a soft lead minie is that, even as much as 5/1000 under bore size, a soft lead minie will still deliver excellent accuracy because the skirt expands to fit the bore. Any hardness in the lead will prevent that optimal expansion, and you will have nothing resembling a group.
Second, about casting. As someone above said, the first several minies are worthless. Your mold has to get real hot before the quality balls fall out. I pitch my first 10 back into the pot. I cast from a Lyman .575213 Old Style at a rate of 2 to 3 minies a minute, and have a reject rate of less than 10% for reasons of voids in the base, bad skirts, etc. With a hot mold and a good lead flow (I use a bottom-pour Lee 20-pound pot), such problems are rare. Just keep it going, and when you pause, set the mold on the pot to keep it hot.
Third, the question of lube. There is GREAT debate amongst those who regularly shoot CW-style minie guns as to the proper lube and its proper application. Some excellent shooters fill only the base with white lithium; some excellent shooters use a 50-50 mix of Crisco and beeswax in both the base and the grooves. Some excellent shooters use a combination of synthetic motor oil and beeswax for only the grooves. The short observation here is that there are many acceptable ways to lube a minie. Personally, I use a plunger-pump device offered by North East Trade Co., (570)546-2061. Comes with MCM lube in a little metal can, two inches high, three across, that I heat up on the stove until the lube is melted, then just push the minie base-down into the plunger and it squirts a little bit up in the base while coating the rings. If you want to tune in the debate on lube, check out the N-SSA bulletin board at
http://www.n-ssa.org/bb/index.php and check the "general posts" for Lube strings. They're plentiful.
Lastly, about your Zouave. I just bought a nice old Navy Arms Zouave from a friend for my son, who is starting to skirmish this year. Loaded it with 37 grains of 3f under the aforesaid minie with MCM lube: First three shots off the bench on Saturday past cut a cloverleaf at 9 o'clock in the 9-ring of a standard N-SSA 50-yard target, an inch-and-a-half out of the x-ring. That ain't bad. Given the right (read soft) minie and powder charge, I'd bet yours will shoot well too. :m2c: