Sons of Liberty Gun Works M4-L89 Upper Receiver Group 5.56 NATO 14.5" M-LOK Plan B Flash Hider

The Sons of Liberty Gun Works M4-L89 is a complete AR-15 upper receiver group chambered in 5.56 NATO, built around a 14.5" Liberty Fighting Barrel pinned to a 16" overall length. The forged upper receiver pairs with a direct impingement gas system sized for the carbine-length platform. A 13.75" L89 seven-sided free-float handguard with M-LOK attachment slots provides a full-length rail interface while keeping the profile lean. The muzzle is fitted with SOLGW's Plan B flash hider, permanently pinned and welded to achieve legal rifle-length overall barrel measurement.