The Davidson Defense Marathon 14.5" Carbine-Gas AR-15 Pistol Full Build Kit delivers a durable and compliant-ready foundation for your next 5.56 NATO build. It features a 14.5" government profile barrel made from 4150 CrMoV steel with a phosphate finish, a 1:7 twist rate, and a carbine-length gas system paired with a 0.750 gas block for reliable cycling.
The included KAK Industry A2 Extended Flash Hider, when installed, brings the barrel length to meet rifle standards, making the kit pin-and-weld ready—though not yet permanently attached. The upper receiver is made from 6061-T6 aluminum with a corrosion-resistant anodized finish, and the 12" M-LOK handguard allows for versatile accessory mounting. A nitride-finished 9310 steel bolt carrier group, mil-spec M4 charging handle, and an SB Tactical SBA3 adjustable stabilizing brace round out this complete, high-performance AR-15 build kit.
Caliber: 5.56x45mm NATO
Barrel Length: 14.5-inch
Barrel Material: 4150 CrMoV
Barrel Finish: Phosphate
Barrel Profile: Government
Barrel Twist Rate: 1:7
Barrel Thread Pitch: 1/2x28
Gas System Length: Carbine
Gas Block Size: 0.750
Upper Receiver Material: 6061-T6 Aluminum
Upper Receiver Finish: Anodized
Handguard Material: 6061-T6 Aluminum
Handguard Color: Black
Handguard Style: M-LOK
Handguard Length: 12-inch
Bolt Carrier Material: 9310 Alloy Steel
Bolt Carrier Finish: Nitride
Charging Handle: AR-15 M4 Charging Handle Mil-Spec Quality
Pistol Brace: SB Tactical SBA3 Adjustable Pistol Stabilizing Brace - Black
Muzzle Device: A2 Extended Flash Hider
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