Main issue with cap and ball revolvers is lack of powder room, which is the reason round balls hit hardest for the old timers. Anything longer reduced the powder and power.
I make what I call a BB (Ball Bullet) for cap and ball revolvers. It's the same height as a roundball, with a substantial flat on a round ball nose, but a bullet base. The flat nose allows it to be seated out a bit for more powder room and better impact on live targets, while the bullet base with grease groove, increases weight a little compared to a round ball, improves accuracy because of better bore grip. They would outperform a WFN, which would have to be speically cut to get them to chamber, and would leave little powder space if made heavy.