I don't know a whole lot about the chemical composition but I'm pretty sure Blackhorn 209 is a nitrocellulose based powder just like smokeless while , triple seven and some of the other are Sugar based. I think there is a big difference between a blackpowder coating as an igniter on a pellet versus mixing 5 gr of a blackpowder substitute that is of a totally different chemical composition with different burn characteristics. Remember that 777 , Goex,APP are all fast burning powders. Only the granular size determines burn rate. That's why recommendations on 2f or 3 f etc.
I wouldn't personally want to be responsible for encouraging someone to do something that might get them hurt in the long run. That's not wise. While experimenting may be fun, it can also be dangerous if there isn't enough knowledge to know the potential ramifications of the experiments.