Ballistic Advantage 16" 5.56 Carbine Length Non-Threaded Barrel - $123.75

[Prudii]

16" 5.56 Carbine Length Non-Threaded CMV Barrel | Ballistic Advantage

They also have a 16" .308 Tactical Government Midlength Non-Threaded AR 10 Barrel - $198.75
16" .308 Tactical Government Midlength Non-Threaded Barrel, Premium Series | AR Replacement Parts

These are being discontinued but are perfect for a complaint build.

 

[ArmedCorgi]

Just bought one! Thnx for the heads up!
Should add that I have one of their 9mm 16" bbl's and it is so far really great.