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Ammonpulver
Unfortunately, AP had two drawbacks that made it undesirable as a propellant. First, since it was based on AN it was extremly hygroscopic, and second, when it was heated to moderate temperatures (32.1øC), a change in the crystalline structure occured, causing the powder grains to crumble. This would cause a drastic increase in the chamber pressure of guns using this propellant, often causing burst tubes.
Since we will be using AP as a bomb filler, however, this becomes a pos- itive asset. It is very cheap to make - about thirty to fort cents a pound - and is quite insensitive to friction. It is, however, much harder to ignite than black powder, so a booster consisting of a few grams of a more sensit- ive compound such as potassium chlorate/sugar or black powder must be used. As a filler for pipe bombs or related items it is without peer.
Preparation:
1) Grind the AN prills in a blender until finely powdered. Sift through a flour sifter, spread out in a shallow pan, and dry for fifteen to twenty minutes in a warm oven. Pour into an airtight jar and seal.
2) Pulverize the charcoal in a heavy cloth bag, then grind in the blender. Sift.
3) Pour 85 percent AN and 15 percent charcoal, by weight, into a rock or case tumbler and add a handful of lead balls. Tumble for several hours. Open and inspect. The contents should be a fine, dark gray powder. It may be necessary to tumble for an additional lenth of time.
AP must be as finely powdered as sifted flour for optimum performance. The hardness of the charcoal is the major obstacle to achieving this state. I find it simpler to buy powdered charcoal (325 mesh) at a chemical supply house as opposed to powdering barbecue briquettes. This form of charcoal may also be found at companies catering to the sign-painting industry.
Ask for "pounce powder". Both the separate ingredients and the completed powder must be scrupulously protected from moisture during all operations. Any device containing AP should be painted with a sealer as a precautionary measure.