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Kak Industry
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.
| Caliber | 5.56 NATO |
| Barrel Length | 13.9" |
| Barrel Twist Rate | 1:7" |
| Barrel Material | 4150 CrMoV, chrome-lined |
| Gas System | Mid-length |
| Muzzle Thread | 1/2x28 |
| Muzzle Device | Brownells PentaComp |
| Upper Receiver | Forged 7075 T6 |
| BCG | K-SPEC Enhanced, chrome-lined phosphate, down-vent design |
| Handguard | 13" M-LOK with heavy-duty barrel nut |
| Charging Handle | Large billet latch |
| Finish | Black |
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.
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.
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.
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.
Kak Industry
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.
| Caliber | 5.56 NATO |
| Barrel Length | 13.9" |
| Barrel Twist Rate | 1:7" |
| Barrel Material | 4150 CrMoV, chrome-lined |
| Gas System | Mid-length |
| Muzzle Thread | 1/2x28 |
| Muzzle Device | Brownells PentaComp |
| Upper Receiver | Forged 7075 T6 |
| BCG | K-SPEC Enhanced, chrome-lined phosphate, down-vent design |
| Handguard | 13" M-LOK with heavy-duty barrel nut |
| Charging Handle | Large billet latch |
| Finish | Black |
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.
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.
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.
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.
