AFTE Store - Modified Griess Test as Part of the Examination Protocol in Shooting Range Determination

Distribution of propellant particles has been used for the estimation of shooting range. The modified Griess test is used to document this distribution. In the absence of such patterns, the modified Griess test would reveal the presence of submicroscopic nitrite particles. However, such particles would not form a pattern for the examiner to estimate the shooting distance. With the advent of digital photography, access to photographic paper for use in the modified Griess test transfer method may be limited. Blotter paper was found to be a suitable alternate transfer medium for this test. Inorganic nitrites exposed to water were found to be lost due to their solubility. One must be mindful of the weathering factors when applying the modified Griess test to estimate the muzzle to target distance. When both the modified Griess test and the sodium rhodizonate test are used in shooting range estimation, one must also be careful that the application of heat in the modified Griess may cause the loss of volatile lead, leading to an erroneous conclusion.