Brownells BRN-4 HK® 416 compatible barrels, available in a variety of lengths and two contours. Historically extremely hard to procure, HK® 416 compatible barrels are now available as part of the BRN-4 lineup. These barrels machined by Faxon, fit early generations of HK® 416 upper receivers and components. They are the perfect fit with the BRN-4 bolt carrier group and gas block (search “BRN-4” for all parts). Available in common barrel lengths of 10.4, 14.5 and 16 inch, these barrels are suitable for any need. You can select the classic “heavy” profile, which is similar to the profile found on earlier HK® 416 models, ensuring barrel rigidity with minimal flex, or you can pick the new “medium” profile, which saves weight and makes the rifle quite handy. Barrels are button rifled with a 1-7 twist and have commonly used ½-28 muzzle threads for the attachment of the muzzle device of your choice. A deep black nitride finish provides an extremely hard exterior and interior, that is easy to clean. The longer barrel extension of the BRN-4 allows for a robust matchup to the upper receiver, and a simple install with the BRN-4 barrel nut (430-100-141). 5.56x45mm NATO chamberings allow for a wide variety of commercially found ammunition to function, as well as 223 Remington cartridges. No need to worry about picking the right gas system length, as all of these barrels have the same piston rod assembly (078-000-644), just be sure to pick the correct BRN-4 gas block to match your overall barrel length, 078-000-708 & 078-000-709). Be sure to pick up the gas block coil pins for final assembly as well (430-103-127). Recommended Barrel Nut Torque: 50-80 ft/lbs.