Ordnance Ballistics Gel Preparation
When making this gel you will likely want to make several batches, so get lots of supplies. I've been told that you should make two or three a day, assuming that you have the refrigerator space.
Gelatin Powder - 1 kg of ordnance gelatin powder or 2 large boxes (32 packets each) of Knox or Kroger gelatin powder.
Distilled Water - 6 liters of water for ordnance or 1 gallon for the packets.
A mold - A plastic container measuring 6" x 6" x 18" or 7" x 7" x 16". You want the container to be standing up and tall instead of laying sideways like a loaf pan. Multiple smaller blocks can't be used - fissures won't expand across blocks.
A mold for the backstop (optional) - Only required if your original mold is smaller than 8" x 8" x 18". Again, a plastic container. The purpose is to catch the bullet, not measure the fissures.
A very large pot - must be able to hold 7.5 liters (2 gallons).
Mixing tool - A drill with a paint mixer, electric beater or whisk. Used to mix in the gelatin powder and remove lumps. This is not optional; a spoon will not make a consistent mixture.
Paper towels and wire mesh strainer - catches the unmixed lumps and filters the mixture
Hearing and eye protection - if you don't automatically pack this when testing weapons, stop now!
Take a couple cups of water and use your mixing tool to mix in the gelatin as well as possible. You're looking to make a sludge so it mixes better later.
Heat the rest of the water to 130°; F ± 10° F (54.4° C ± 5.6° C) in the very large pot. There's going to be foam, so make sure that you have plenty of room to spare.
Add in the gelatin goo. Add it in slowly and mix it well.
Put a layer of paper towels on the mesh to make a filter.
Use a large spoon to scoop off foam. Dispose of in the sink with running hot water.
Coat mold with silicone spray to make removal easier.
Put the filter over your mold. Either get it rigged up to stay there or get a friend to hold it.
Pour the gelatin into the mold through the filter to remove the foam and lumps.
Let stand for 4 hours at room temperature, with aluminum foil tented over the mold to prevent airborne contaminants.
Place into refrigerator at 39° F (3.9 ° C) for 24 hours or more.
Remove gelatin from mold. Pour a small amount of ice cold water between the mold and the gelatin to ease removal. Running warm water on the outside of the mold will help out if it remains stuck.
Blot water from block using paper towels.
Wrap gelatin in a plastic bag.
Return to 39° F (3.9 ° C) refrigerator and wait at least another 24 hours.
Use a cooler to transport the gelatin. Do not add ice otherwise it may skew the results. Shoot a steel BB into it at a velocity of 590 fps ± 30 fps (180 m/s ± 9 m/s). It should penetrate 3.35 inches (8.5 cm). If you don't shoot at the right speed, it will penetrate just a bit more or less, so a tiny amount of variation may be noticed.
When doing testing professionally, one would only use the block for a single shot. Fissures from the first shot will skew results of all subsequent shots.