Ballistic Gel Recipe Done Correctly For Regulation 10% by Weight and Proper Density
I'm a retired cop and have made both ballistics gel and used off the shelf unflavored gelatin,
The bellow recipe has worked for me for over 13 years. It gives the best results and as long as the steps are followed exactly and will result in calibrated FBI regulation ballistic gel. I got this recipe from firearmstactical.com back in 2000 and its given better results than any other manufacture steps.
Calibration of finished product by FBI staandard:
Complete calibration by using a air rifle or pistol shooting a steel BB into it at a velocity of 590 feet per second ± 30 fps. The BB should penetrate 8.5 centimeters. This test done on bare gel block with no fabric or clothing in front of the target.
Step 1: What You Will Need
- Vyse type 250A ordnance gelatin powder (1 kilogram) or 1kg Knox brand unflavored gelatin, 6 boxes give you just over 1kg of powder
- Triple beam balance
- Stainless steel or Pyrex mixing bowl (3 quart)
- 5 gallon plastic paint bucket
- Graduated pitcher (3 liter) or measuring cup (1 liter)
- Thermometer (capable of measuring fluid temperature of 130° F ± 10° F)
- 9 liters hot tap water (130° F ± 10° F)
- Electric drill
- Paint stirrer (w/ plastic propeller-type blades)
- 12cc hypodermic syringe
- Aquarium air hose (6 inches long)
- Propionic acid
- Large spoon
- Silicone spray mold release
- Gelatin mold (FBI size: 6"W x 7"H x 16"L)
- Refrigerator (capable of maintaining approximately 39° F)
- Thermometer (capable of measuring air temperature of 39° F ± 10° F)
- Kitchen size (13 gallon) plastic garbage can bags
- Ice chest (if transporting gel to range or outdoors and not using immediately)
- Stand for block, cheap or built wood table
- Pneumatic air rifle capable of shooting steel BBs at 590 fps
- Ruler, metric (45 - 60 centimeters)
- Dial caliper
- Denim cloth (14.5 - 16 ounce) or other clothing patch or layers of clothing and coat to simulate clothing interaction.
Step 2: Mixing Procedure
Note: If balance does not have capacity to measure 1000 grams, measure two 500 gram portions or four 250 gram portions. I f gelatin powder is scooped into a container and the container is placed on the balance, be sure to take the container's weight into consideration or your gelatin powder weight will be incorrect. Weigh the container first and add the container's weight to the desired weight of the gelatin powder to be measured. If you're measuring two 500 gram portions of gelatin powder and the container weighs 75 grams, set the balance to measure 575 grams.
2. Using graduated pitcher/measuring cup, measure 6 liters hot tap water (130° F ± 10° F) into 5 gallon plastic bucket.
3. Add 1 kilogram pre-measured gelatin powder to hot tap water while slowly mixing with paint stirrer attached to electric drill. Pour and mix approximately 1/3 of the pre-measured gelatin powder at a time, ensuring all gelatin powder is thoroughly mixed before adding more. (If you add the gelatin powder while mixing, be careful that the airflow produced by the electric drill doesn't blow the gelatin powder all over your work area. We found it best to pour about 1/3 of the powder directly into the water, and then turn-on the drill to mix it thoroughly before stopping to add more powder.) Exercise care to prevent entrapment of air in gelatin solution.
4. After 1 kilogram gelatin powder has been thoroughly mixed into 6 liters hot tap water, use syringe to measure and add 5 milliliters propionic acid to gelatin solution to inhibit mold growth. (Propionic acid is not necessary if you intend to shoot the gelatin block within a week after preparation and you intend to dispose of the gelatin block immediately after testing.)
5. Add 3 liters hot tap water (130° F ± 10° F) to gelatin solution. Slowly mix gelatin solution for 3 - 5 minutes, ensuring all gelatin powder is dissolved. Exercise care to prevent entrapment of air in gelatin solution.
6. Use large spoon to scoop off foam from surface of gelatin solution. Dispose of foam in sink while running warm tap water.
7. Spray gelatin block mold with silicone spray mold release for ease of gelatin block removal. (Ensure gelatin mold is clean and dry. Small particles of dried gelatin solution adhering to internal surfaces of mold can produce gouges in gelatin block when it is removed from the mold.)
8. Carefully pour gelatin solution into mold.
Step 3: Remove Gel Block
2. Place filled mold, uncovered, in refrigerator at 39° F.
3. Wait at least 24 hours before attempting to remove gelatin block from mold.
4. When removing gelatin block from mold, pour a small amount of ice cold water between mold and gelatin to ease removal. After gelatin block is extracted from mold, blot water from block using paper towels.
Step 4: Cure Gelatin Block
2. Gelatin is ready to shoot when 48 hours old. Larger gelatin blocks may require additional time to properly cure before use.
3. Use ice chest (add no ice) as an insulated container to transport ordnance gelatin to shooting range. Use thermometer inside ice chest to monitor temperature.
Note: A couple of milk containers, filled with water and frozen solid, can be placed into the ice chest to cool the interior. The milk containers should be put inside the ice chest at least couple of hours prior, and removed immediately before placing the gelatin block inside. Do not add any ice to the ice chest after the gelatin block has been placed inside. Doing so will produce temperature variations throughout the gelatin block, and invalidate your test results.
4. Remove gelatin block from ice chest, unwrap it, and place it on test stand. Position chronograph sensors (skyscreens/photoelectric screens) directly in front of gelatin block to measure projectile impact velocity
Note: Time is of essence. Depending on ambient air temperature, the gelatin block will begin to warm as soon as you remove it from the ice chest. It's best to test in an environment in which the ambient air temperature is 65° F or cooler. A good rule of thumb to follow is to complete your testing within 20 minutes after removing the gelatin block from the ice chest. If you believe a gelatin block may have warmed, verify it meets calibration standards.
Step 5: Calibrating, Using and Measuring Results
Note: We use a calibration standard of 7.7 - 9.4cm BB penetration (corrected) at 590 fps velocity. This provides a calibration tolerance of plus or minus 10 percent. As long as the BB achieves this range of penetration/corrected penetration, we consider the data to be valid as measured.
2. If two or more gelatin blocks are going to be lined-up end-to-end to capture the entire wound path of the bullet under test, each and every gelatin block must be calibrated in accordance with step 17.
3. After calibrating, the gelatin block(s) is ready for terminal ballistics testing. Depending on the cartridge being tested, more than one bullet can be shot into the block(s). Carefully plan each shot to avoid overlap of previous temporary cavities/bullet paths, and to ensure the bullet will not exit the sides or top of the block.
4. It's best to measure penetration depth after each shot is completed. This practice minimizes loss of data if one bullet collides with another in the gelatin block.
5. After penetration depth is measured, the bullets can be recovered at a later time to measure expansion diameter using dial caliper.
6. If denim cloth is used to test bullet expansion performance, cut a 4 feet long, 6 inch wide strip of cloth. Fold the cloth strip lengthwise twice. This produces a cloth test fixture that's 1 foot long and four layers thick. Place the cloth loosely against the gelatin block, half on top of the block, half hanging over the front of the gelatin block.
7. If shooting at an outdoor range, shade the gelatin block from direct sunlight using a piece of cardboard or similar device.
Guide to recycling gel after testing:
VYSE is one if the leading ballistic gel manufactures and the what most PDs and the FBI use in testing. This is a link to their ballistic gel brochure and in it their mixing instructions for their gel powder.