Ballistic gelatin

Ballistic gelatin is a testing medium scientifically correlated to swine muscle tissue (which in turn is comparable to human muscle tissue), in which the effects of bullet wounds can be simulated. It was developed and improved by Martin Fackler and others in the field of wound ballistics. Ballistic gelatin is a solution of gelatin powder in water. Ballistic gelatin closely simulates the density and viscosity of human and animal muscle tissue, and is used as a standardized medium for testing the terminal performance of firearms ammunition. While ballistic gelatin does not model the structure of the body, including skin and bones, it works fairly well as an approximation of tissue and provides similar performance for most ballistics testing. Ballistic gelatin is used rather than actual muscle tissue due to the ability to carefully control the properties of the gelatin, which allows consistent and reliable comparison of terminal ballistics. Ballistic gelatin is a testing medium scientifically correlated to swine muscle tissue (which in turn is comparable to human muscle tissue), in which the effects of bullet wounds can be simulated. It was developed and improved by Martin Fackler and others in the field of wound ballistics. Ballistic gelatin is a solution of gelatin powder in water. Ballistic gelatin closely simulates the density and viscosity of human and animal muscle tissue, and is used as a standardized medium for testing the terminal performance of firearms ammunition. While ballistic gelatin does not model the structure of the body, including skin and bones, it works fairly well as an approximation of tissue and provides similar performance for most ballistics testing. Ballistic gelatin is used rather than actual muscle tissue due to the ability to carefully control the properties of the gelatin, which allows consistent and reliable comparison of terminal ballistics. The most commonly used formula is a '10% ballistic gelatin', which is prepared by dissolving 1 part 250A bloom gelatin into 9 parts of warm water (by mass), mixing the water while pouring in the powdered gelatin. It is chilled to 4 °C (39 °F). The older NATO formula specifies a 20% solution, chilled to 10 °C (50 °F), but that solution costs more to prepare, as it uses twice the amount of the gelatin. In either case, a 1988 research paper by Martin Fackler recommends that the water should not be heated above 40 °C (104 °F), as this can cause a significant change in the ballistic performance. To ensure accurate results, immediately prior to use, the gelatin block is 'calibrated' by firing a standard .177 caliber (4.5 mm) steel BB from an air gun over a gun chronograph into the gelatin, and the depth of penetration measured. While the exact calibration methods vary slightly, the calibration method used by the INS National Firearms Unit is fairly typical. It requires a velocity of 183 ± 3 m/s (600 ± 10 f/s), and a BB penetration between 8.3 and 9.5 cm (3.25 to 3.75 inches). In his book Bullet Penetration, ballistics expert Duncan MacPherson describes a method that can be used to compensate for ballistic gelatin that gives a BB penetration that is off by several centimeters (up to two inches) in either direction. MacPherson's Figure 5-2, Velocity Variation Correction to Measured BB Penetration Depth, can be used to make corrections to BB penetration depth when measured BB velocity is within ±10 m/s of 180 m/s. This method can also be used to compensate for error within the allowed tolerance, and normalize results of different tests, as it is standard practice to record the exact depth of the calibration BB's penetration.