Yup Catfish, that's exactly why I bought it. Since then, it's loaded a thousand or more black powder rounds.
The reason for not using a ferrous metal in a BP measure is the same reason they don't use ferrous metals in the manufacture of BP and substitutes, risk of ignition. The Lee measure and the old Lyman 55 are known to be safe with BP. Since I'm using fillers with my 1858 Smith cartridges, I've been looking at what meters well in a Uniflow since my Lee and Lyman are occupied. Being a son of the South, I've been using grits as a filler but cream o wheat meters better through a Uniflow so I guess grits are only for sausage and gravy again.