More 777 information:
http://www.forensic-testing.net/uplo...xp_summary.pdf
777 contains, among other stuff, Potassium nitrate, Potassium perchloride, Benzoic acid (na salt), Nitrobenzoic acid (na salt) and Dicyandiamide.
BTW: Some bomb squads and labs have problems identifying 777 from pipe bomb residue.