Tannerite is the brand name of a binary explosive marketed primarily for making exploding targets for firearms practice. It is a patented combination of ammonium nitrate (an oxidizer) and aluminum powder (a fuel) that is supplied as two separate powders which are mixed and shaken to produce the explosive. The combined explosive is relatively stable when subjected to less severe forces than a high-velocity bullet impact, such as a hammer blow, being dropped, or impact from a low-velocity bullet or shotgun blast. It is also not flammable – an explosion cannot be created by a burning fuse or electricity. Because it is sold as two separate powders rather than as the combined mixture, it is even more stable when sold, and can be transported and sold in many places without the legal restrictions that would otherwise apply to explosives. Tannerite is the most well-known brand of such a product – to the degree that sometimes such combination explosives are generically referred to as Tannerite, although other brands exist on the market
Smooth bore 37mm projectile launcher - not a DD. Not even a title 1 firearm. This item falls under the "not a weapon" (signaling device) exception. Generally a large bore device for which no anti-personnel ammo has ever been made will NOT be a DD. This used to be true of the 37mm guns. However, according to ATF, some folks have started making anti-personnel rounds for these guns, and ATF has ruled that possession of a 37mm launcher and a bean bag or rubber shot or similar round is possession of a DD, and at that point the launcher needs to be registered. Put another way, before you make or buy anti-personnel rounds for your 37mm launcher, register it as a DD. The rounds themselves, not being explosive, incendiary or poison gas, are not regulated in themselves either. It is just the two together. See ATF Ruling 95-3.
Flame Thrower - not a DD, nor even a firearm. Unregulated as to possession, under federal law. Great way to clear snow off the driveway.