.300 AAC Blackout
The suppressed-SBR sweetheart — just keep 300 BLK mags religiously separate from 5.56, because a Blackout round chambered in a 5.56 gun is the classic catastrophic mix-up.
Family
Rifle
Introduced
2011
Origin
Advanced Armament Corp (Robert Silvers), from J.D. Jones's .300 Whisper, USA
History
AAC standardized J.D. Jones's .300 Whisper concept as the .300 Blackout in 2011, giving the AR-15 a .30-caliber cartridge that needed only a barrel swap and ran superbly suppressed. It leads a double life: fast supersonic loads for short barrels, and heavy subsonic loads that turn a suppressed AR into a whisper. It's become the suppressor community's home cartridge.
What it's used for
Iconic platforms
Short-barreled ARs and AR pistols, SIG MCX Rattler, and bolt guns like the Ruger American Ranch.
Common load types
Supersonic FMJ and soft point, subsonic heavyweights built for suppressors, and expanding hunting loads.
Reference only — not loading data, not ballistics advice, and KitID links to no ammunition sellers. Know your local law before you buy anything that goes bang.