I did a bit of Google-fu and found Dick Dastardly's Big Lube website. His designs are unique and I have zero doubt that they will work as advertised.
Some years back, I got it into my head to try The Holy Black in some firearms I own that were appropriate for that ancient fuel. I am no BPCR maven, and the mixed results detailed herein will bear that out. I should add that Rick Tunell (AKA "Buckshot" in other realms) was very helpful in these ventures, and once I REALLY started paying attention to what he related my satisfaction level increased markedly.
The correct alloy--somewhere between pure lead and 25/1 Pb/Sn--is important. I used 30/1 alloy throughout, in 45/70--44/40--and 32/20 calibers. I also used Steve Garbe's SPG lube for all loads, flood-lubed and sized in Lyman 450/H&I dies after the flooded bullets were cookie-cuttered from the congealed and cooled puddle-in-can-lid I used to apply the stuff. Was it messy? Nah, not much worse than sizing/lubing with a 450 usually gets. And SPG smells nice.
What matters--POWDER QUALITY. I have zero doubt that DD's Big Lube Bullets were designed to address the cagao black powders that most BPCR shooters are saddled with, at least when they start. This was (at the time of these experiments, about 20 years ago) almost always Goex, AKA "Flaming Dirt". Proper BP-specific lube is a big help, also. So too is sufficent amounts of lube for each shot. Hence the SPG, which was coin-of-the-realm back then. Sizing was spec'ed the same as that used in smokeless loads--throat specs.
45/70--Lee 405 grain bullets--there was enough lube capacity in the 4 shallow Lee grooves to enable uninterrupted shooting and CONSIDERABLE accuracy, even with Goex 2F. 100 yard results were many 1-1/2" to 1-3/4" 5-shot groups (55.0 grains, 1/16" compression, no wads). The substitution of Swiss 2F (60.0 grains, same compression) yielded the best grouping I ever got from that rifle (Ruger #1), 1-1/8" to 1-1/4" at 100 yards/5 shots.
44/40--Lee 200 grain round flatnose with 2 shallow grooves--2 words, twice--unmitigated disaster. Epic fail. Insufficient SPG and Goex 3F @ 35.0 grains combined to create very hard fouling within 6 shots that resulted in bullets tumbling downrange. Mining the bore's encrustation was a PROJECT, though a MacGyvered system using fishing line, a small bell sinker, and cotton patches did keep most of the corrosive fouling out of the action. Those Win '73 removable sideplates are a Godsend for BP cleanout, too. Maybe better powder and/or more lube might have altered the outcome. A look today at Dick's 200 grain "Mav Dutchman" 44 caliber bullet design brought back not-so-fond memories of garden hose/sprayer into my '73's action. I am sure it saw worse things during its service as a ranch gun in the early 20th Century, but given his historical gravitas such processes are a mite scary to conduct.
32/20--Lyman #311008, a borrowed tool that cast BIG......315". No, the owner won't part with it. Drat him, anyway. "008" carried enough SPG to keep things running well and smoothly for 50 shots in my Colt Bisley x 4-3/4". Again, its historic provenance gives me the fantods when I use the water sprayer/blow dryer/oil routine after firing BP in the thing, but it has survived my care sequences in good order so far.
The Marlin 1894CL (The One That Got Away) in 32/20 did OK with the BP loads for about 15-17 shots before accuracy went south. Hard fouling at the muzzle-end of the barrel was easily removed--a spit-soaked cotton patch or 2 on a 30 caliber rod jag, and we were back in business. One fouler, and the grouping returned to "reasonable". A "Big Lube" 32 caliber bullet would very likely keep a 32/20 levergun shooting all day, if you were so-minded.
Black powder shooting is NOT for those of us who tend toward laziness at the end of a day's shooting. You gotta clean those guns most ricky-tick when the sun slides toward the western horizon. Same story with the cartridge brass--gotta be washed out. I liken it to my boat's upkeep after a day or a week in salt water--you need some fresh water to get the evil chemicals away from your metal and wood, or BAD THINGS will happen.
Is black powder enjoyable? Oh, absolutely! The boomy reports, the clouds of smoke, and sulphur odor--what's not to like? I think Dick Dastardly's line of Big Lube Bullets addresses a true problem faced by BPCR and revolver shooters brought on by cruddy black powders that the trade forces upon recreational shooters. There are still good BPs available in this country, most are imports. I have not tried any of the Goex "Old Eynsford" line of fuels yet. One of my front-loaders will be the first victim to test-drive this fuel, when I get around to it. Don't hold your breath, though.