I have a small amount of PB and Solo 1250. I am now using THE HOLY BLACK FOR MY ELSIE.
Black powder requires some cleaning after shooting but it is good with an Elsie. I'm using Federal paper hulls with nitro cards, fiber or wool felt wads with no shotcups (nickel plated shot helps reduce barrel leading). They work just fine. You get to shoot your gun and its choke as it was designed to shoot.