By way of explanation...
BP substitutes are purposely designed to be harder to ignite, to satisfy DOT and other regulations with respect to shipping and storage. Those regulations have made the availability of Holy Black spotty at best these days. I drive a couple hours to my favorite source, and purchase Goex Cartridge, FFFg, and FFg one-pound cans by the dozen.
It's also why you won't see Pyrodex used in the flash pan of a flintlock.
"Bother", said Pooh, as he chambered another round...