300 Blackout vs 5.56: AR-15 Cartridge Guide 300 Blackout vs 5.56 is one of the most useful AR-15 cartridge comparisons for shooters choosing between standard rifle speed and heavier .30-caliber performance. Both cartridges can work in AR-15 platforms, but they are built for different needs. The 5.56 NATO is the better choice for most shooters […]