Brownells Government Barrel Assemblies - Chrome Lined and Individually Inspected The Brownells Government Barrel Assemblies are manufactured by a US Government Contractor for M4 barrels, and held to exacting standards. These barrels all feature a hard chrome bore, applied over button rifling. Each barrel is High Pressure Tested, followed by Magnetic Particle Inspection & Gauging to ensure there are absolutely zero imperfections. Assemblies are as ready-to-install as possible, with slip ring assembly, F-Marked front sight base and handguard cap pre-installed. Handguard caps are appropriate for the barrel length, with M4 Carbine assemblies featuring a round cap, and the rifle Mfg: Brownells