 In the spring of 1962 Remington submitted the specifications of the .223 Remington to the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI).With the U.S. military adoption of the M16 assault rifle in 1963, the .223 Remington in a slightly derived form was standardized as the 5.56×45mm NATO.As a commercial sporting cartridge the .223 Remington was introduced in 1964.