What pressures do Pyrodex pellets operate at?

[RugerNo3]

Loading Black Powder granules and the various substitutes in metallic cases requires that there be no dead air space. Pellets of the same propellents will have dead airspace. To get consistent results, it would be best to follow the manufacturers recipe and be consistent with sizing, seating and case capacity.
The cowboy crowd is shooting close range with those handguns.
Bullet grouping is not a requirement. Take those pellet loads to 50yds and check the grouping.
Any one I know has gone back to loose powder after trying pellets in their muzzle loaders do to inconsistent accuracy. There's no free ride for that.