AR-15 compatible .30-caliber cartridge optimized for short barrels and suppressor use. Uses standard AR-15 magazines, bolt, and lower receiver — only the barrel changes. Supersonic loads (110–150gr) offer good terminal performance; subsonic loads (190–240gr) are significantly quieter than supersonic rounds when suppressed, though still audible without hearing protection at approximately 130–140 dB.
Type: Rifle
Introduced: 2011, United States
Parent case: .221 Remington Fireball
Standardization: SAAMI
Bullet diameter: 0.308" (7.82 mm)
Case length: 1.368" (34.75 mm)
Overall length: 2.26" (57.4 mm)
Max pressure: 55,000 PSI
Rim type: Rimless
Primer: Small Rifle
Typical twist rate: 1:7
Muzzle velocity: 1000–2375 fps
Muzzle energy: 450–1400 ft-lbs
Effective range: 460 yd
Common bullet weights: 110, 125, 147, 150, 190, 208, 220, 240 gr
Primary use: Military, Hunting, Self Defense
Production status: Active
Also known as: .300 BLK · 7.62x35mm
History: Created in 2011 by Advanced Armament Corp for special operations. Goal was .30-caliber performance in AR-15 magazines with excellent suppressed performance. Uses same bolt as 5.56 NATO.
Notable firearms: AR-15, Honey Badger, MCX, various AR pistols
Military use: {"country":"United States","years":"2011-present","conflicts":["Various SOCOM operations"]}
Similar cartridges: 7.62x39mm, .30-30 Winchester