I tried bullets from three moulds, at 55 yds. with 55 grains of Triple 7 2F: 1) Lee "old style" Minie with thin skirt, 2) Lee "REAL" bullet, and 3) Lee "Improved Minie" with much thicker skirt. The first two miked at .575 average with the "improved" Minies miking at about .576-.577. I dip lubed them in SPG.
First off, I'm NSSA and we shoot for speed AND accuracy.
Only ONE mold design from LEE has worked in any of my muskets, and it isn't one you listed. It's a discontinued "target" minie that looks like a standard, flat nose wadcutter. It's very accurate, the rest, no. This mold in 58 is discontinued but you might be able to score one on ebay. This particular LEE mold is only in 575, I haven't seen it in any larger ones. Since all but one of my muskets run 579, this mold is a non starter for all but the one. In that one, it's a tack driver at 50yd. And of course, only pure lead.
For a good selection of test bullets, go to the Bulletman on Lodgewoods page. He's NSSA and makes a very good bullet. Find one that works, then buy the mold.
Best accuracy so far for me, other than that ONE Lee design- RCBS Hogdon, Rapine Trashcan (nearly identical to the Lee and also out of production although Moose makes one very similar), Lyman 577213.
Powder- ditch the subs and run only real deal black. Get the best quality you can afford. I've found Swiss 3f to be the ticket. Goex standard gets close, but it takes more powder to get same velocity, hence the extra expense of Swiss is offset by lower charge levels. In nearly every musket, 60%ish of service charge will deliver best accuracy, all other variables held constant.
Caps, another variable to control. Avoid CCI reenactor ones like ebola if you want accuracy. RWS/Schutzen are the best ones.
Lube can have a HUGE affect on accuracy. Take a known load, change lube and it can either open way up, hold the same or get better. You have to experiment. I've found, in general, beeswax/lard(or tallow) delivers the best accuracy. In controlled testing, lard/tallow out performs crisco in every load tested.
Finally, go over to the NSSA home page and look at the links section, click on "sutlers" and you'll find Moose, Lodgewood, and others. DGW isn't the go to it used to be.
Finally, even with "target" ammo, if all the variables are properly controlled, you can shoot many rounds in succession and the gun will only be as fouled as the first 2 or 3. We did a marksmanship/instruction project with the Scouts this summer and I routinely ran a 63 Remington Contract (aka Zouave) over 40 rounds with no wiping nor loss of accuracy. The gun was still capable of shooting off the clothespins and wires holding targets at 30+ rounds.