Introducing the Brownell's Retro A1 16" carbine length barrel assembly. Chambered in 5.56x45mm NATO, the chrome lined barrel is available with 1-7" rifling and finished in black phosphate with an overall length of 16". Muzzle threads are A 1/2"-28, and in back there's a standard barrel extension. Each Retro A1 16" carbine barrel assembly includes a front-sight base, .625", no F marks, complete with sight post, detent, spring, sling swivel, rivet, flat Delta ring, barrel nut, weld spring, snap ring, and round handguard cap installed. Machined from 4150 chrome moly steel. The barrel you need for your next Retro Rifle build! Mfg: Brownells