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. Since ballistic gelatin mimics the properties of muscle tissue, it is the preferred medium for comparing the terminal performance of different expanding ammunition, such as hollow point and soft point bullets. These bullets use the hydraulic pressure of the tissue or gelatin to expand in diameter, limiting penetration and increasing the tissue damage along their path. While the Hague Convention restricts the use of such ammunition in warfare, it is commonly used by police and civilians in defensive weapons, as well as police sniper and hostage-rescue teams, where rapid disabling of the target and minimal risk of over penetration are required to reduce collateral damage.
By using such a tool in criminalistics law enforcement can use bullets shoot out of a firearm that is thought to be the weapon is question as a comparison to one that was either found at the crime scene, or removed from the victim. Being that ballistic gelatin is the same density of human muscle, the marks on the bullet would then show similarities between it and one removed from a real body. It has help to convict many suspects to the murder of a victim.
MacPherson, Duncan (1994). Bullet Penetration: Modeling the Dynamics and the Incapacitation Resulting from Wound...