The Benefits of Using the 300 Blackout Cartridge The 300 Blackout cartridge is a relatively new cartridge. It was developed to replace the standard 5.56x45mm cartridge that is used in AR-15 rifles. The 300 Blackout cartridge is designed for use with a .30 caliber bullet and it has an https://that-site76531.blogdanica.com/14055657/the-complete-guide-to-300-blackout-and-what-it-means-for-you