If you are building a new modern sporting rifle in .308 Winchester, consider the MK216 upper assembly from Primary Weapons. It features a 16" threaded barrel with muzzle brake and an extended KeyMod handguard. This would work well for any rifle purpose from hunting to target and competition, especially for those planning to run their rifle suppressed. The upper assembly will pin onto any standard DPMS-profile .308 lower receiver.
Specifications and Features
Primary Weapons M216UCOB
16" 4140 steel threaded barrel with muzzle brake
Flat top upper receiver