A .45 caliber bullet exiting the spent gunpowder. This event takes place approximately 6 inches in front of the gun. The gunpowder still has velocity and will travel up to 20 feet from the point of discharge. This gunpowder can be detected on clothing and skin to determine the location of individuals at the scene of a crime. The schlieren optical system images different air pressures with different colors of light. This image freezes the motion by using a high speed flash with a duration of 1/2,000,000th of a second.