Daniel Defense 16 inch Cold Hammer Forged, lightweight profile barrel.  Machined 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, M4 ramped barrel extension with 1:7 twist rate, .750 diameter gas block journal, carbine length gas system, and 1/2-28 threaded muzzle.

Rock River Arms 20 inch, air-gauged, cryo-treated, stainless steel, HBAR barrel, chambered in .223 Wylde with a 1:8 twist, .750 gas journal diameter, rifle-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.

Daniel Defense 18 inch Cold Hammer Forged, S2W (Strength to Weight) profile barrel.  Machined 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.  Salt-bath nitride finish, 5.56 NATO bore and chamber, M4 ramped barrel extension with 1/7 twist rate, .750 diameter gas block journal, rifle-length gas system, and a 1/2-28 threaded muzzle.

Rock River Arms 18 Inch Mid Length Fluted No Font Sight

5.56mm NATO Chamber, 1:9 twist, threaded 1/2-28, with barrel extension and pin. Weight 37.9 ounces.