The .300 Blackout is one of the more interesting calibers in recent years, officially approved by SAAMI in 2011, and born out of a need for a specialized close-combat round for special operations units, the .300 AAC Blackout has become one of the most popular chamberings for the AR-15 platform – and for a good reason.
Offering better ballistic performance and stopping power than the standard 9mm (the most popular subsonic SMG round) in subsonic AR setups, and you can run standard 5.56 magazines with any rifle chambered in .300 Blackout as the case dimensions are close enough to function in both.
