The mannequins wearing hats experienced an average of 18.9
percent less heat loss than mannequins without hats, states authors of «Head Insulation and Heat Loss in Naked and Clothed Newborns Using a Thermal Mannequin,» published by Medical Physics Online in June 2002.
«You get
less than 10
percent loss of velocity, and friction from the bullet passing out creates enough
heat to reseal the window,» says Fred Williams, Labock's vice president.