Definitions for ".22 BB"
BB Cap (Bulleted Breech Cap) is a variety of .22 caliber rimfire ammunition .22 BB cap and .22 CB refer to cartridges that are low velocity and project reduced noise. These rimfires are closely resemble a .22 caliber air rifle in power and are often used for indoor shooting and close range pest control. Developed for indoor shooting galleries with special "gallery guns", the .22 BB Cap was the first rimfire cartridge, dating back to 1845.