This full build kit centers on an 11.5 inch KAK Industry .223 Wylde barrel with a carbine gas system and 1:8 twist, built for versatility across both .223 Remington and 5.56 NATO ammunition. The government profile barrel is nitride treated 4140 CrMoV steel, delivering heat resistance and surface hardness that hold up under sustained fire. The upper receiver is machined from 7075 T6 aluminum with an anodized finish, paired with a lightweight 6061 T6 aluminum M-LOK handguard that keeps the front end manageable without sacrificing rigidity. The kit includes a complete bolt carrier group with a 9310 steel bolt head and 8620 steel body, both nitride finished for wear resistance, along with a mil-spec charging handle and a micro low-profile gas block sized at 0.750 inches. The Gauntlet Arms polymer stabilizing brace provides a solid shooting platform, and the GI A2 birdcage flash hider threads directly onto the 1/2x28 muzzle.
Key Features
Perfect For
The .223 Wylde chamber specification splits the difference between .223 Remington and 5.56 NATO, allowing you to run either cartridge without the pressure concerns that come from firing 5.56 in a dedicated .223 chamber. The 1:8 twist rate stabilizes common bullet weights from 55 to 77 grains, making this barrel a practical choice whether you're running bulk training ammo or heavier precision loads. The carbine gas system in an 11.5 inch barrel sits right in the sweet spot for reliable cycling without excessive port pressure, and the nitride treatment on the 4140 CrMoV steel adds a hard, slick surface that resists carbon buildup and throat erosion.
The 7075 T6 aluminum upper receiver brings the strength needed for bolt lockup and pressure containment, while the 6061 T6 aluminum M-LOK handguard keeps weight down where it matters most. M-LOK slots run the length of the handguard, giving you modular attachment points for lights, grips, or bipods without adding permanent rail weight. The micro low-profile gas block tucks under the handguard with a 0.750 inch diameter fit, keeping the profile clean and eliminating snag points. The anodized finish on both the upper and handguard provides corrosion resistance and a consistent black appearance.
The included bolt carrier group uses a 9310 steel bolt head, a material choice that offers superior strength and fatigue resistance compared to standard Carpenter 158 steel. The 8620 steel carrier body is nitrided for surface hardness and lubricity, reducing friction during cycling and extending service life. The mil-spec charging handle provides a reliable grip surface for charging and malfunction clearance, and the micro gas block meters gas flow without the bulk of a traditional front sight base.
The Gauntlet Arms polymer stabilizing brace delivers a rigid shooting platform with a high-strength polymer construction that handles recoil without flexing. The GI A2 birdcage flash hider is a proven design that disrupts the flash signature at the muzzle, reducing visible flash during low-light shooting. The 1/2x28 thread pitch is the industry standard for .223 and 5.56 muzzle devices, so swapping to a different brake, compensator, or suppressor mount is straightforward.
Follow safe handling and manufacturer instructions
Ensure compliance with all applicable laws
Verify component compatibility before use
Inspect all components prior to use
Product: Strata w/Gauntlet Arms Brace 11.5-inch Carbine-Gas 1:8 .223 Wylde AR-15 Freefloat M-Lok Handguard Pistol Full Build Kit
Caliber: .223 Wylde
Barrel: KAK Industry 11.5" .223 Wylde Carbine Gas Government Profile Barrel
Barrel Length: 11.5-inch
Barrel Material: Nitride 4140 CrMoV
Barrel Thread Pitch: 1/2x28
Barrel Finish: Nitride
Barrel Profile: Government
Barrel Twist Rate: 1:8
Barrel Gas System Length: Carbine
Upper Receiver: AR-15 Upper Receiver
Upper Receiver Material: 7075 T6 Aluminum
Upper Receiver Finish: Anodized
Handguard Material: 6061-T6 Aluminum
Handguard Color: Black
Handguard Style: M-LOK
Charging Handle: AR-15 M4 Charging Handle Mil-Spec Quality
Bolt Carrier Group: AR-15 5.56/.223/.300/.350 Complete Bolt Carrier Group
Bolt Carrier Material: 9310 Alloy Steel (Bolt Head), 8620 Alloy Steel (Body)
Bolt Carrier Finish: Nitride
Gas Block: Micro Low-Profile Gas Block
Gas Block Size: 0.750
Muzzle Device: AR-15 1/2x28 TPI GI Birdcage Flash Hider 5.56 .223 A2
Muzzle Device Details: Effectively reduces flash signature and muzzle rise
Muzzle Thread Pitch: 1/2x28
Pistol Brace Information: Gauntlet Arms Polymer Stabilizing Brace - Black
Pistol Brace Material: High-Strength Polymer
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