RE: 4F Blackpowder--WTH is it?
You can prime with FFFg with only a little slower lock time. Dixie's catalog for years suggested grinding FFg or FFFg with a silver spoon in a china cup. You could use a brass rod, or any non-sparking material to grind with, though. If you do go to the trouble to get some FFFFg, a one pound can will last a loooooong time. I think my last can of it has lasted two years, and I still have about 1/2 pound left.