300 Blackout is a favorite caliber among both the short-barreled rifle crowd and those with suppressors. Also known as .300 AAC, this caliber excels at offering ballistic stopping power at subsonic speeds. Although it doesn’t offer the longer range capabilities of some other rifle ammo offerings, 300 Blackout is a perfect choice for short and mid-distance engagements. Available in both steel and brass case options, .300AAC is often more expensive than its 5.56 counterpart but is a go to for many looking for a home defense or “truck gun” caliber when paired with a suppressor.

Note that gas setup on a 300 Blackout AR-15 style rifle will take some planning and adjustment for proper cycling. With the wide range of ammo options in subsonic and supersonic, an adjustable gas block is suggested. Pair that with a suppressor and back pressure and further adjust will be needed. All that said, .300AAC is a great option for a defense AR setup.