FirearmsID.comThe introduction to firearm identification includes fundamentals, bullet basics and identification, caliber, general rifling characteristics, cartridge case identification, striated action marks, and impressed action marks. There are also sections on distance determinations, case profiles, ballistic gelatin, an introduction to ballistics, and a history of firearm identification. The resource area is for registered users only, however registration is free. These resources include graphic libraries, firearms identification quizzes, and the AFTE glossary.