I've been thinking some more about your question regarding using FFFFG for the main charge in your Old Army Ruger.
And here's my latest thinkin' on it,....
You say one of the reasons for trying FFFFG, is to increase velocity,.... one thing you gotta remember is, when shooting pure lead round balls, in a fast-twist barrel, with shallow riflings,... the less likely the bore's "lands" will maintain their "grip" on bare, soft, pure lead balls as velocity encreases.
That's why for most cap'n ball pistols,... a "less than" full cylinder of powder is usually more accurate than a full cylinder, and it's higher velocity.
Also,... "leading" of your bore, will become a real concern as velocity is increased,.. since there is no way to put "gas checks" on round balls,... and even if you could,.. pushing them into a cylinder would be impossible when loading.