dreadnaught, I've shot a ton of Lyman 429667s through my Bisley Vaqueros and Rossi 92. No leading! Break in on these guns was about a hunert rounds each with jacket stuff. I used to use super moly lube, but now use home made. I have had excellent results with Unique in the 44 Spl cases and Green Dot in the mag cases-loads are on the Alliant web site, although many other powders would work equally well I am sure.
Hardness does not necessarily equate to no leading. It could be other things causing your problem such as the throat, velocity, or maybe the bullets are TOO hard. Yup, that's right.
btw, the Lyman 429667 is a flat round nose that feeds lever guns like there's no tomorrow. sundog