Tannerite is is certainly real. The composition dates way back before Mr. Tanner decided to use it as a mail order explosive. In earlier days the material was readily available to magicians as "flash powder." It was usually sold in very small quantities to minimize the risk associated with nixing. Tanner ships the stuff in larger containers of the two components.

Mixing the substance is hazardous because of the high sensitivity to friction, especially when the process is performed on on the scale of ounces.

The explosive is essentially the same stuff used to make firecrackers. In such applications the contents of each charge is limited by law to 50 miligrams. Larger units (generally illegal) were called cherry bombs or M-80s.

The professional fireworks industry uses similar compositions in much larger quantities for bursting charges. There have been numerous accidents in this applications from premature ignitions in the mortars used to launch the charges.

There was a case a few years ago in which a guy blew his hand off with a Tannerite charge he had loaded into a 38 mm bird bomb. The lawsuit was eventually dropped on the basis that you cannot aqueeze blood from a turnip.

A interesting property of the explosive is that it lies in the nether region between deflagrating and detonating materials. Although technically a so-called "low explosive," functioning by a diffusion-limited reaction, it will readily explode with a loud bang and dangerous overpressure in the absence of confinement.