Ask ten AR-15 owners what caliber their rifle should be chambered in, and you'll probably get ten different answers. From 300 Blackout to 6.5 Grendel to 6.8 SPC, the modern sporting rifle market is flooded with alternative chamberings promising better terminal performance, more range, or heavier bullet weights. With so many options competing for attention, it's fair to ask: is 5.56 NATO still worth it? The answer is a resounding yes — and here's why this decades-old cartridge continues to …