Headstamp-to-Headstamp is our series aimed at helping you grok everything ammo.
Today, two of the most popular caliber choices for AR-15 style rifles and pistols are in the go-to standard that is 5.56 NATO, and the newer, but no less versatile, .300 AAC Blackout.
Choosing between the two takes a little thought and boils down to the intended purpose the gun is set to fill, with the two calibers being very different in background, terminal ballistics, performance, and use.
