Hmmmm, interesting threads. I just started to convert over to Black Powder. OK, not quite there with the real holy black as a buddy of mine gave me 1/2 dozen cans of pryodex. What can I say, free powder is free powder. BUT I have had a lot of success with it. My rifle is a uberti 73, 24 inch barrel, 45 colt. I started out using Lymans 250 grain cowboy bullet (452-664) but with spg, (It does have a large than normal lube grove, though not quite as big as DD) and 32 grains of pryodex, WLP pistol primer. One thing I make sure of is a day or two before the match, I pretty much scrub out the barrel. Yeah Yeah, I've been know to "over clean" my firearms. (Gunny Sgt Camp, my DI years ago would be proud) Its a Marine thing. Then I run a couple of patches saturated with bore butter and let it sit overnight. Then run a clean patch thru it. My brass is RP and I've annealed the mouths with an annealing maching I got years ago when I was shooting NRA High Power. I've made it through about 150 to 160 rounds with no problems. Before I started annealing, I'd get all kinds of blow by into the action that I's have to stop and do a quick cleaning about the 4 or 5 th stage. Not any more.
I do have DD ROA mold also (the new on too) I use that primarily for my pistol loads in my vaqueros and my ROA. Its about 210 grains. I havnt tried it in the rifle. I have a preference for a longer heavier bullet in the rifle.
The key to my world is bullet lube, lots of it, and barrel prep