Abstract: A classification system and identification key for .177 caliber air gun pellets was developed based on a five-class characteristic criterion. Sixty-eight pellet types from 15 companies were examined and compared. A classification system was developed based on the pellets’ head shapes, skirt types, lengths, weights, and other markings or observations. In some cases, when a pellet is recovered from a crime scene, product brand identification may aid the investigation. Even though all product brands cannot be identified, various brands of pellets can be eliminated based on a pellet’s class characteristics. The pellet producers in this study were located in the following countries: China, Czech Republic, England, Korea, Spain, and the United States. An identification key can be used for possible pellet identification or elimination.