i have a remington 1858 with the brass frame, a long barrel 8 or 9'' i think
i havent shot it in a long time anyway...
one time i fired pellets out of it just for the heck of it.
i loaded a light charge of powder, 10 grain i think, put in a wadding (paper works, packed the wadding, added about 25-30 pellets of #8 size shot and more paper wadding to hold it in place. something a little more advanced that nokebook paper would probaly give better results.
from about 7 paces the shot covered a 6'' area, might be useful for showing off and shooting hand thrown clays with your revolver, or snakes...
a black powder revolver isnt a shotgun, but necessity is the mother of invention right?