Ammonpulver (AP).

  AP was developed in the late 1880s as a replacement for black powder. It
is an intimate mixture of 85 percent ammonium nitrate and 15 percent char-
coal. It was used by Germany and Austria as an artillery propellant until
nitrocellulose-based powders became commonly available. It was extremly
powerful, being on a par with double-based powders containing 30 percent 
nitroglycerine, and was virtually smokeless and flashless.
  Unfortunately, AP had two drawbacks that made it undesirable as a prop-
ellant. 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.

