Here is the method I followed. I'm not sure what might have gone wrong. I attempted to "calibrate" last night and a BB penetrated over six inches.
Maybe the block wasn't adequately cooled. I'll try another BB this evening.
BALLISTIC GELATIN MIXING PROCEDURES PRACTICED BY THE FBI
In December 1988, the FBI Academy Firearms Training Unit (FTU) designed and implemented the FBI Ammunition Tests. The test designs are based on research and consultation with experts in the fields of wound
ballistics, forensic pathology, wound research and medical research. The tissue simulant utilized in FBI ballistic tests is Vyse Ordinance Gelatin.
The mixture is 10%, by weight. The mentioned research shows that properly calibrated 10% ordinance gelatin is a reliable tissue simulant. Calibration of ballistic gelatin is verified by firing a .177 steel BB at 590 feet per second (fps), plus or minus 15 fps, into the gelatin, resulting in 8.5 centimeters (cm), plus or minus 1 cm, penetration (2.95" – 3.74"). During FBI tests, any gelatin blocks, which fail the calibration test, are discarded. Calibration results are not published due to the Pass/Fail nature of the test.
Mixing Gelatin
The gelatin is mixed in the following manner (assuming a twenty-pound block is desired)
1) Weigh out two (2) lbs. of gelatin powder and place aside
2) Weigh out 18 lbs. of hot 60° C (140° F) water in a plastic bucket. (Note: The FBI utilizes a scale, which
weighs to the nearest .01 lb)
3) Place 2.5 ml of Foam Eater in water
4) Place approximately .5 ml. of oil of cinnamon into water (prevents fungus growth)
5) While utilizing a battery-operated drill with a mixing paddle attached, mix the water to the point of forming a whirlpool, without introducing air into the mixture
6) While the water is being mixed, slowly add the gelatin powder
7) Pour the mixture into a clean mold pan
8) Allow to stand at room temperature for approximately 4 hours
9) Write date on small square of cardboard and place on top of mixture
10) Place pan with mixture into refrigerator set at 4° C (39.2° F)
11) Allow curing for 36 hours (note: larger blocks require longer cure time. (e.g. an 80lb block requires 96
hours to cure) Blocks, over time, deteriorate and are temperature sensitive. Former FBI publications advocated utilizing blocks within 20 minutes of removal from the refrigerator, a general statement pertaining to ambient temperature
indoors). Allowable time outside the refrigerator is, however, relative to the temperature of the test environment (e.g. a block removed from a refrigerator and maintained in a room at the same temperature as the refrigerator will retain its calibration significantly longer than one placed outside on a hot summer day). Note: Some authorities believe mixing procedures may vary the consistency of gelatin. FBI studies indicate, however, that a block, which displays the required level of penetration, within the required velocity range, is a “valid” tissue simulant. The FBI Ballistic Research Facility conducts its tests in an environmentally controlled shooting laboratory. The blocks of gelatin are removed from the refrigerator and checked for calibration. Only valid blocks are used for test.
Blocks used in testing of conventional pistol ammunition are approximately 6.25" X 6.25" X 16". The initial block of gelatin used in a test is referred to as “The Primary Block”. Each Primary Block is utilized for a maximum of five shots, one in each corner, approximately 1.75" from the nearest edge, and one in the center. Tests conducted by the FBI indicate this placement of shots results in substantially the same penetration as single shots into virgin blocks of gelatin. Any shots, which cross the wound path of previous shots, are re-fired. Primary blocks are not utilized for more than five shots, to include any shots, which are re-fired. Because some shots may penetrate more than one block of gelatin, one or more “stopper” blocks are placed behind the primary block. The stopper blocks may be utilized for more than one test, if the wound channels are not crossed. At the end of each test, the stopper block is placed back into the refrigerator while another stopper is utilized with an unused Primary block. Stopper blocks may receive more than five penetrations; if no wound channels are crossed, (e.g. a stopper, which has five penetrations of 3” into one end, can be flipped over and used as a subsequent “stopper.”) The FBI does not reuse gelatin. Used blocks are discarded.