NOTE: This is a blow back design. A gas tube and gas block are not needed.The barrel is one of the most critical components of your build. We only offer high quality barrels so you can be confident that your rifle will be off to a good start with which ever barrel you decide on.NOTE: This barrel has a "tapered stop" machined into it. If you would like to mount a front sight post on it, please use a mid-length hand guard.Features: 16" Length Barrel 1/10 Twist Rate 1/2 X 28 Thread Pitch for Muzzle 9mm Luger Chamber .750 Gas Block Seat Black Nitride In and Out Tapered Profile Weight: 1lb 12oz