Rock River Arms 18 Inch air-gauged, cryo-treated, stainless steel, varmint barrel chambered in .223 Wylde with a 1:8 twist, mid-length gas system, and a non-threaded, target crown muzzle.  The Barrel Diameter is .920 in front of the gas block and 1.050 behind.  Also included is RRA's Single rail gas block with gas tube roll pin.

Rock River Arms Stainless Steel 24 Inch Varmint Barrel chambered in .223 Wylde (accepts both .223 and 5.56 ammunition) Air-Gauged, Cryo-Treated, and available in 1/8 twist. The Barrel Diameter is .920 in front of the Gas Block and 1.050 behind. Also included is RRA's Single rail gas block with gas tube roll pin. 

Daniel Defense 16 inch, Cold Hammer Forged, lightweight profile barrel.  Manufactured from ordnance-grade 4150 Chrome Moly Vanadium alloy steel for exceptional strength, and magnetic particle inspected (MPI) to ensure there are no internal flaws in the metal.  Chrome lined 5.56 NATO bore and chamber with 1/7 twist,  M4 ramped barrel extension, “F” marked front sight tower, midlength gas system, .750 diameter gas block journal,  and 1/2-28 threaded muzzle.

Rock River Arms 16 inch Air-Gauged and cryo-treated Stainless Steel, H-Bar barrel chambered in .223 Wylde with a 1:8 twist, .750 gas journal diameter, mid-length gas system, and a 1/2-28 threaded muzzle.

The .223 Wylde chamber was designed as a match chambering for semi-automatic rifles. It will accomodate both .223 Rem and 5.56mm NATO ammunition. It is relieved in the case body to aid in extraction and features a shorter throat for improved accuracy.