A few years ago, Steve Garbe's "SPG Black Powder Cartridge News" had an article on the .30 Wesson. I think that @ one time Steve Garbe may have toyed w/ the cartridge.

I'd contact the magazine & see if you can obtain a reprint of the article.

Screwloose- Go ahead and try the Black. My Winchester (1-10 twist) loves it (Swiss FFF) behind a Hoch 177gr. Shoots far better than the nut behind the butt.

Screwloosetc
     Up front let me say that the rifle I had built is for hunting (small critters, rocks, prairie muffins, etc.), not target work. I am not a competitive shooter. That being said, I do regularly test loads at our local range and this one will keep inside MOA (100 yds) if I do my part. Remember, "Only accurate rifles are interesting." SPG is my choice in lubes as that is what I started with many years ago and I have seen no reason to change. The longest string I have shot is 12 rounds before cleaning (cool + dry conditions.) Again in a hunting situation there is no opportunity for wiping between shots. I do use a blow tube and fowling so far has not been an issue for me. The 1-10 twist was chosed for the heavier hunting bullets I wanted to use per advise I received from other sources. I read the Garbe article many years ago but if my memory serves me correctly I believe he thought the 1-12 twist would stabilize the lighter slugs better for less recoil over long shot strings at targets? With the heavier hunting bullets, this cartridge can surprise you with its bark. Yes, black will give you enough velocity within the perameters of what the cartridge was designed for. I had a thread started on the WSU Forum years ago and received help from a gentleman there during my first trials with the cartridge. You could try a search for more info.
Remember, my opinion is worth exactly what you paid for it. 

Flatlander