CMMG MK4 300 AAC Blackout 16.1" Barrel Finish Adjustable Stock Round Semi-Automatic Rifle RCE 4140CM

The 300 AAC Blackout (300 BLK) was developed in 2009/2010 by Advanced Armament Corporation and approved by Sporting Arms and Ammunition Institute (SAAMI) in 2011. Based on the 223 Remington case necked up to 30-caliber, it was intended for the M4 Carbine and designed to function in standard AR15/M16 magazines. Thus converting an AR to 300 AAC Blackout requires nothing more than an upper receiver group. Dimensionally it is identical to the 300 Whisper, but the 300 Blackout is fully standardized. Supersonic and subsonic ammunition is manufactured, with a 125-grain bullet producing 2215 feet per second, while the subsonic load uses a heavier bullet at much lower velocity: 220-grain bullet at 1080 fps. Military applications are obvious; as a sporting cartridge performance is similar to the 7.62x39. — Craig Boddington