The 20" 5.56 NATO barrel assembly has a military A2 HBAR profile. The barrel has a 1/8 twist, and it includes all the parts needed to attach it to an upper receiver.
Caliber: 5.56 NATO | .223
Diameter at the gas port: .750"
Barrel Threading: 1/2x28
Barrel Profile: A2 Heavy Barrel (HBAR)
Barrel Material: 4140 Chrome Moly Vanadium
Twist Rate: 1/8
Bore & Barrel Lining: Chrome Moly
Barrel Coating: Manganese Phosphate
Sight: F-marked A2 front sight with a side sling swivel
Handguard: Thermoplastic Handguards with Double Heat Shields
Gas System: Rifle Length
Muzzle Device: A2 Flash Hider (Post ban will have a pinned in place muzzle brake)
Q: Will this work with my upper receiver?
A: The barrel assembly will work with any mil-spec upper receiver.
Q: Do you provide instructions on how to install the barrel?
A: Unfortunately we don't provide directions on how to install a barrel and recommend that it be installed by a gunsmith to prevent damage to the rifle.
Q: Do I have to purchase a matched bolt to my barrel?
A: With AR-15 rifles, as long as you are using the proper bolt for the caliber you do not need to match a bolt to the barrel.