AR-15 Model 605 A1 15.5" Rifle Length Barrel Assy 1-12 FSB

Correct Barrel for a Replica of the First M16-Based Carbine

This Retro barrel assembly has the correct A1 contour and length (15.5") for a replica of the Model 605, Colt’s first attempt at an M16-based carbine. The Model 605 barrel was a standard A1 rifle tube that was cut off just ahead of the front sight tower. The nub end was re-threaded, and the A1 rifle flash suppressor was simply reattached! The rest of this "carbine" - buttstock, buffer, gas tube, etc. - remained just as the rifle, so the result is a short (approx. 34" OAL), heavy-set weapon whose pugnacious stance we find kinda cool. Of course, Colt would go on to build a "proper" carbine, the CAR-15. But if you want to build an accurate replica of that first carbine prototype... this is the barrel you need.

Otherwise, our Model 605 15.5" barrel assembly gives you all the features of our other A1 Retro barrels. It’s machined from hardened 4150 steel, then MPI inspected to detect hidden flaws (so we can pull it from the supply chain BEFORE it ever leaves the factory), and given a hard black phosphate finish similar to the original M16s / CAR-15s of the 1960s. It’s chambered for the modern 5.56 NATO cartridge, but with the slower, 1960s 1-12" rifling in the chrome-lined bore.

• Correct A1 contour & 15.5" length for Model 605 prototype carbine
• Ordnance grade 4150 chrome-moly carbon steel
• Tough matte black phosphate Parkerized finish
• 5.56 NATO chambered with 1-12" twist rifling
• Uses RIFLE LENGTH gas tube (not included)
• Many other lengths & contours available - see separate listings

Up front, the Retro A1 barrel for the Model 605 carbine has standard ½-28" tpi muzzle threads, ready to accept a "retro" flash suppressor or modern muzzle device / sound suppressor. On the other end there’s a standard rifle barrel extension already installed. Also installed: a 625" gas block/front sight base (no F marks & no bayonet lug) with sight post, detent, spring, sling swivel, Delta ring, barrel nut, weld spring, snap ring, and triangular handguard cap.