Ol Gabe,
I have long found that you can readily lump the BPs into two categories, those that create lots of powder fouling (Goex, Dupont, Elefant, etc.) and those that create much less (Swiss, Pyrodex, 777, apparently also Schutzen (limited personal experience, many excellent results reported). With the cheap ones -- Goex, etc. -- the excellent old BP bullets often don't carry enough lube to counter all the powder fouling from these cheap powders. With Swiss, Pyrodex, 777, etc. the amount of powder fouling is so much less that these bullets work really well, just as they did well over a hundred years ago, also then with widely available premium BPs.
The same nice old BP bullets that shoot for many, many tens for shots with no group-opening accumulation of powder fouling with Swiss, Pyrodex, 777 etc. will all too soon be giving unacceptable groups when used with Goex, etc. for the simple reason that there has arisen 10-20+ cm of hard, difficult to remove BP fouling in the muzzle end of the barrel. That totally unnecessary accumulation of BP powder fouling is the "hard-to-clean" mess I was referring to. With one brand of 44-40 BP ammo using Goex, the crud buildup is so rapid and severe that withing 10 shots the group at 25 yards was in the 8-10 inch range -- totally unacceptable and totally typical for normally adequate 2-lube groove bullets.
One of the things seemingly not widely recognized is that Swiss BP leaves about as little powder fouling as Pyrodex and 777. That is one of the essential features leading to its well deserved reputation. I now shoot either Swiss FFG or 777 FFG in my CAS BP loads. It is rather difficult to tell the difference in performance, cleaning, amount of powder fouling, etc. SO, IF someone wants to use "Real BP" AND also wants premium performance with proper, authentic, time-tested BP bullets and excellent lubes, they should pay the few extra dollars for Swiss. IF, instead, they want to use gobs and gobs of grease, or, take other measures to counter all the BP powder fouling, they should use Goex, Elefant (also KIK?).
Modern duplicates of the really excellent, premium BP loads of the late 1800s provide really excellent performance. Performance essentially totally free of the usually adverse aspects of BP loads. Aside from the sometimes bothersome aspects of BP smoke, these loads give up absolutely nothing to modern nitro loadings in the old BP cartridges.
Lars