"Not a smokeless powder, but approved to be shipped as such", is what you will find on the msds sheets of pyrodex and triple se7en. What makes those powders different than true smokeless powders? The lack of nitrocellulose. True smokeless powders are nitrocellulose based. Pyrodex is just souped up black powder and triple se7en lacks the sulfur component. Also, pyro and 777 are classified as "pyrotechnic mixtures" whereas smokeless powders are simply "propellants".