Investigation of the impact of a sound suppressor on the weapon's memory effect and gunshot residue formation

The firearm's memory effect describes circumstances where particles from previous firing cycles are deposited with or incorporated in the new ammunition debris. Even though this phenomenon is well studied, the influence of a sound suppressor on the strength of the memory effect and its extent has not yet been investigated. In this study, the SINOXID-type ammunition barium, antimony lead with added aluminum (BaSbPbAl) primer mixture, was initially fired, followed by firing ammunition with classic SINOXID primer composition BaSbPb. Thirty bullets were test fired with and without a suppressor, accompanied by sample collection in predetermined shooting intervals. The results of the present study demonstrate that the memory effect was significant even after 30 shots of the latter classic SINOXID ammunition, both with a suppressed pistol or unsuppressed pistol, and that the proportion of the particles not compatible with the primer composition was unequivocally pronounced when using a suppressed pistol. Moreover, shooting a suppressed pistol affects the total amount of gunshot residue found on the shooter's hands; thus, it should always be considered in reconstructions of shooting incidents. Explanations for this phenomenon are offered.