.300 AAC Blackout, .300 BLK, 7.62x35mm
**WARNING** In firearms that use a floating firing pin (such as the AR-15 and its variants), dropping the bolt on a chambered round could lead to a slam fire. It is important that these firearms are loaded from the magazine so that the bolt loses inertia when it strips a round from the magazine. It is also important NOT to use sensitive primers that aren’t designed for use in an AR, as this increases the chance of a slam fire.
The .300 Blackout is based on a shortened 5.56x45mm case that is necked to .30 caliber. For AR-15 platform rifles and pistols, changing the barrel only requires going from 5.56 to .300 Blackout. The Blackout's main purpose is to be used at subsonic velocities in suppressed firearms. Many bolt action and single shot rifles are now being produced in this caliber as well.
