This upper build kit pairs a 14.5-inch 4150 CrMoV barrel with a carbine-length gas system, designed for shooters building a compact AR-15 pistol platform. The barrel comes pin/weld ready, and the aircraft-grade aluminum handguard supports M-LOK mounting for accessories. All components are finished in phosphate for corrosion resistance.
The pin/weld ready configuration allows you to permanently attach a muzzle device to meet legal requirements without additional modifications. The barrel threading and pin holes are pre-machined, so you can proceed directly to attachment at a qualified gunsmith. This setup is common for pistol builds where overall length compliance matters.
A carbine-length gas system cycles faster than longer alternatives, which suits shorter barrels well. The 14.5-inch barrel paired with carbine-length tuning creates a balanced platform that handles 5.56 NATO across a range of ammunition types. The 1:7 twist rate stabilizes standard and heavier bullet weights effectively.
This upper assembly fits standard AR-15 lower receivers with mil-spec dimensions. The M-LOK handguard accepts standard M-LOK accessories. The 1/2x28 thread pitch accommodates common muzzle devices designed for 5.56 NATO platforms.
Follow safe handling and manufacturer instructions. Ensure compliance with all applicable federal, state, and local laws. BCG and charging handle are not included.
Caliber: 5.56x45mm NATO
Barrel Length: 14.5-inch
Barrel Material: 4150 CrMoV
Barrel Thread Pitch: 1/2x28
Barrel Finish: Phosphate
Barrel Profile: Government
Barrel Twist Rate: 1:7
Barrel Gas System Length: Carbine
Gas Block Size: 0.750
Gas Block Finish: Phosphate
Gas Block Material: Steel
Upper Receiver Material: 6061-T6 Aluminum
Upper Receiver Finish: Anodized
Handguard Material: Aircraft-Grade Aluminum
Handguard Color: Black
Handguard Style: M-LOK
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