Elmer Keith, in his book "Sixguns," used ffg in his 1851 Navy. He loaded to within a felt wads thickness of the top of the cylinder, and then seated the ball on top of the wad, compressing the load. He said the gun would cut clover leafs all day at twenty yards. I would try it, but black powder is impossible to find here. I don't think I mis-read him, but that seems like a lot of compression for the powder. I would start lighter and work up to it.
Elmer recomended ffg in revolvers .36 and larger.