The barrel is one of the most critical components of your build. We only offer high quailty barrels so you can be confident that your rifle will be off to a good start with which ever barrel you decide on.Features: 20" Rifle Length Barrel MIL-B-11595E CMV Chrome Lined 1/7 Twist Rate 1/2 X 28 Thread Pitch for Muzzle 5.56 Nato Chamber .750 Gas Block Seat M4 Feed Ramped Barrel Extension MilSpec Phosphate Coating HBAR/ A2 Profile Rifle Gas Weight: 3lb 6oz