Is it Possible to Accurately Identify a Shooter's Face as Illuminated by   the Muzzle Flash of a 22 LR Pistol?
  The science of firearms muzzle flash has been dominated by three perspectives: 1) Does the muzzle flash reveal friendly positions to naked eye observers so as to draw fire from enemy combatants? 2) Can flash signatures be recognized by electronic surveillance with sufficient accuracy to identify source firearms? 3) Is the muzzle flash so bright as to diminish the night vision of friendly forces during a firefight? This paper addresses a fourth question: Does the muzzle flash of a specific cartridge provide sufficient duration and intensity of illumination with visible light to allow observers to positively identify a shooter's face? The experiment used two shooters firing a total of 20 shots from a 22 LR semi-automatic pistol. Shooters fired in randomized order, while eight observers (male US military veterans) attempted to identify the shooter for each trial shot. The firing range was mostly darkened with only enough ambient light to safely conduct firing tests at the direction of a range safety officer. There was not enough ambient light to identify the shooter's face. Observers correctly identified the shooter 54% of the time and failed to correctly identify the shooter 46% of the time. Observers were unanimous that there was no hint of any visible illumination on the shooter's face provided by the muzzle flash. In cases where the shooter was correctly identified, observers reported using visual cues such as the sillhouette of the shooters' hair and slight differences in arm positions when firing the pistol. Other people in the room (including the author) were in unanimous agreement that there was no illumination of the shooters' faces from discharge of a 22 LR pistol. 
Michael Courtney
physics.pop-ph