As has been discussed on the Forum many times before, the old pistol cartridges (.45 Colt, .44WCF etc.) were loaded with a powder finer than our 4F.
I started experimenting with 2F and 3F, of GOEX, (and some 4F powder given me by a friend who quit shooting flintlock, which I assume is also GOEX) in my Uberti 1858 Remington. Got up to 35 grains of 4F when I realized my chronograph readings were off, due to muzzle blast tripping the "start" screen. Unfortunately, I had to quit then, and haven't been able to get back out. ( Life gets in the way, and I had a lot more time before I retired!)
However, the 4F didn't blow up my gun, and I prefer 2F or 3F for priming my flintlock, so the fine stuff will get used as main charge for my revolvers.
I will post figures when I get back out with the chrono.
Apologies to the OP for running astray of the thread...but I was addressing another poster's question.
Richard/Grumpa