Lot of good information here. Some confusing comments also.
As one who has been using traditional muzzle loaders for 90% of my shooting, including competitively, for over 40 years, I have seen and tried many techniques. As for 777, I won't even comment as I use and understand only true black powder in the old timers.
For the revolvers a seal is absolutely necessary. I do know guys who boast they shoot without a seal but I also know some who have had chain fires without. Many, maybe most, competitive c&b revolver shooters use an over-ball grease seal. Some use corn meal under the ball, a few do use wads. I never have used a meal seal, messy and unnecessary, IMHO. Most of my shooting has been with an over ball grease seal. For hunting and long term storage, I have used lubed wads, they are just fine. I believe they provide a good shooting seal but can't prove that. They do help clean the bore a little. Remember, the burning powder crud is behind the wad and waits for the next shot. Main rule is to use what works for you and keep it simple.