"M27" inspired 5.56x45mm Barrel for the BRN-4(TM) platform Not previously available in this configuration, the BRN-4 M27 16.5 inch 5.56x45mm NATO chrome lined barrel features a forward mounted bayonet lug. Manufactured by Faxon for Brownells, these manganese phosphate barrels are machined from 4150 chrome moly steel, and feature a precision buttoned rifle 1-7 twist bore with chrome lined 5.56x45mm NATO chamber. The bayonet lug attaches after installation of the gas block. The bayonet lug installs the same way as the gas block, with a simple coil pin driven in from the side. This makes for an extremely robust mount for a bayonet. Be sure to use a BRN-4 16" ga Mfg: Brownells