SI Defense AR-15 Barrels are made from 4140 chrome moly steel and use button rifling. The barrel is chambered in 300 AAC Blackout with a 1 in 8" Twist. The M4 profile is light under the handguard and .750" at the gas block with the M203 cut. The muzzle is Threaded 5/8"-24 to accept muzzle brakes, flash hiders, or a sound suppressor. The barrel is finished with a mil-spec manganese phosphate finish and includes a pre-installed barrel extension and locator pin.
The 300 AAC Blackout (7.62x35mm) squeezes 30 caliber firepower into the traditional AR-15 envelope, and is available in either subsonic or supersonic ammunition varieties to serve a multitude of purposes. All that is needed to harness the enhanced performance of the 300 Blackout is a simple barrel swap; the bolt, carrier, magazine and all other components remain the same as those used in a traditional 223 Rem/5.56 NATO rifle.
- Length: 16"
- Material: 4140 Chrome Moly Steel
- Contour: M4
- Chamber: 300 AAC Blackout (7.62x35mm)
- Twist Rate: 1 in 8"
- Chrome Lined: No
- Finish: Mil-Spec Heavy Phosphate
- M4 Feed Ramps: Yes
- Muzzle Thread Pattern: 5/8"-24
- Gas Port Location: Carbine
- Exterior Diameter at Gas Port: 0.750"
- Gas port comes set for supersonic ammunition. It may need to be enlarged to fire subsonic ammunition.