Franklin Armory M4-SBR-M Milita with Pinned & Welded Triumvir Muzzle Device 308 Winchester 14.5in Hard Coat Anodized Semi Automatic Modern Sporting Rifle - 20 Rounds - The M4-SBR-M MILITIA Model Carbine is Franklin Armory's 7.62mm NATO/308 Winchester battle rifle with factory-installed BFSIII binary trigger. This is NOT a SBR, as the 14.5in barrel has the Franklin Armory Triumvir muzzle device pinned & welded. NOT a SBR: 14.5in barrel has the Franklin Armory Triumvir muzzle device pinned & welded