The .300 Blackout (also known as 7.62x35mm) was developed by Advanced Armament Corporation (AAC) in collaboration with Remington Defense in the late 2000s. Its creation was driven by the need for a versatile cartridge that could function well in both supersonic and subsonic configurations, particularly when used with a suppressor. The concept behind the .300 Blackout was to create a round that would perform better than the 5.56x45mm NATO, especially in short-barrel rifles and suppressed setups, while maintaining compatibility with standard AR-15 platforms.
The U.S. military and special forces were a major influence on the development of the .300 BLK, as they sought a cartridge that could be more effective at close ranges and work seamlessly with sound suppressors. The 5.56 NATO, while effective at longer ranges, was known to lose performance in short-barrel rifles and was less than ideal in suppressed scenarios. This led AAC to design the .300 Blackout using a .223/5.56 case, necked up to accommodate a .30 caliber bullet. This allowed the .300 BLK to work in AR-15 rifles with only a barrel change, making it highly adaptable for military, law enforcement, and civilian use.
Released in 2011, the .300 Blackout gained popularity rapidly due to its versatility. It could fire supersonic rounds in the 110- to 150-grain range for more traditional rifle uses, offering ballistics similar to the 7.62x39mm (the AK-47’s cartridge). It also excelled in subsonic loads with heavy bullets, such as 220 grains, which are ideal for suppressed shooting. This made the .300 BLK an attractive option for tactical applications, home defense, and hunting, especially for those who preferred a quieter, more efficient round.
The .300 Blackout has since become a widely accepted round in the firearms community, prized for its ability to perform in a variety of scenarios. It’s used by law enforcement, military, and civilian shooters alike for everything from close-quarters combat to hunting large game. Its flexibility, especially with suppressed weapons, has cemented it as one of the most popular alternatives to the 5.56 NATO in modern AR-15 platforms.
