What about RPG's?
I thought it was funny...
Unless you have a special license for various jobs (Special effects coordinator, blast mining, etc) that require them, it's very hard to get your hands on any type of explosive materials. For example, after the Oklahoma City bombing (where the guy allegedly used fertilizer) it's difficult to even purchase large amounts of fertilizer!
Also, RPG's aren't very popular in the states. It's a Russian weapon (later adopted and manufactured by the Chinese as well) that was heavily distributed on the European, Asian, and African continents, but not much elsewhere. Central America (Mexico/Cuba) sees some RPG action, and there do exist RPG's in the states, but very few.