.300 AAC Blackout

The .300 AAC Blackout (designated as the 300 BLK by the SAAMI and 300 ACC Blackout by the C.I.P.), also known as 7.62×35mm is a rifle cartridge developed in the United States by Advanced Armament Corporation (AAC) for use in the M4 carbine. Its purpose is to achieve ballistics similar to the 7.62×39mm Soviet cartridge in an AR-15 while using standard AR-15 magazines at their normal capacity. Care should be taken not to use 300 BLK ammunition in a rifle chambered for .223/5.56 or 7.62×40mm Wilson Tactical.