THESE BARRELS PROVED TO BE SO POPULAR THAT WE DECIDED TO MAKE THEM A REGULAR ITEM* Chamber- 5.56 NATO* Length- 16"* Gas system0- Mid Length* Gas Block Size- .750* Threads- 1/2-28* Finish- Nitride * Twist- 1:7* Material- 41V50* Extension- M4 Feed Ramps* Barrel dimpled for gas block set screw* Weight 29.97 OZ* Marked for Caliber and Twist* Fully Made In House From KAK Industry Produced BlanksAll Barrels Are Air Gauge Inspected for Correct Bore Size & Tolerances, completed Barrels are Inspected for Proper Headspace using Calibrated Gauging.