K-Spec 5.56 Nato 13.9'' Bbl 1-7 Twist Complete Upper Black

The KAK Industry K-Spec 5.56 NATO complete upper with 13.9" barrel and 1-7 twist is a ready-to-run rifle upper built for shooters who want accuracy, reliability, and suppressor compatibility out of the box. This is a factory-assembled upper receiver—just bolt it to your lower and you're shooting. It pairs a chrome-lined 4150 CrMoV barrel with KAK's K-SPEC Enhanced BCG, a down-vent design that redirects gas downward instead of into your face, a significant advantage when running a suppressor with a traditional baffle can.

The 13.9" barrel length sits in that sweet spot for versatility: short enough for CQB and vehicle work, long enough to wring decent velocity from 5.56 without a permanent muzzle device. The 1-7 twist rate stabilizes everything from lightweight varmint rounds to heavy 77-grain match ammunition, so you're not locked into one load profile. You get a Brownells-exclusive PentaComp muzzle device (1/2x28 threaded) and a 13" M-LOK handguard with a heavy-duty barrel nut for a rock-solid shooting platform. The forged 7075 T6 upper receiver and large billet latch charging handle complete a package designed for years of service. Each upper is test-fired before it ships to confirm reliable function.

Built in the USA and engineered around mid-length gas system tuning, this upper works well for suppressed and unsuppressed shooting alike. If you're building a short-stroke AR or upgrading an existing lower, this complete upper eliminates guesswork and assembly headaches.

Key Features

• Chrome-lined 4150 CrMoV barrel, 13.9", 1-7 twist rate, twice stress-relieved
• K-SPEC Enhanced BCG with down-vent design, chrome-lined phosphate finish, and dual ejectors—redirects gas downward for suppressed shooting
• Forged 7075 T6 upper receiver
• Mid-length gas system
• Brownells-exclusive PentaComp muzzle device, 1/2x28 threaded
• 13" M-LOK handguard with heavy-duty barrel nut
• Large billet latch charging handle
• Chambered in 5.56 NATO
• Test-fired for function verification
• USA made

Specifications

Frequently Asked Questions

Will this upper work with my AR-15 lower?

Yes. This is a complete upper receiver assembly that accepts any standard AR-15 lower receiver. No additional work or parts are required—the upper is fully assembled and test-fired.

Is this upper good for suppressed shooting?

Yes. The K-SPEC Enhanced BCG features a down-vent design that redirects exhaust gas downward instead of toward the shooter's face, which is a significant advantage when running a suppressor with a traditional baffle can. The mid-length gas system also contributes to smooth suppressed operation.

What ammunition will the 1-7 twist stabilize?

The 1-7 twist rate is versatile and will stabilize a wide range of 5.56 NATO ammunition, from lightweight varmint rounds to heavy 77-grain match ammunition.

What's included in this upper?

This is a complete upper receiver assembly ready to attach to a lower receiver. It includes the barrel, bolt carrier group, muzzle device, handguard, charging handle, and all necessary hardware. No additional parts are required to make it functional.