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  3. Davidson Defense Marathon w/Magpul BTR Brace 14.5-inch Carbine-Gas 5.56 NATO AR-15 Pistol Full Build Kit Pin/Weld Ready with KAK Industry A2 Extended Flash Hider

Davidson Defense Marathon w/Magpul BTR Brace 14.5-inch Carbine-Gas 5.56 NATO AR-15 Pistol Full Build Kit Pin/Weld Ready with KAK Industry A2 Extended Flash Hider

Part Number: PI-PK-556-63531-BTR
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On sale $399.99 $299.99
Retail Price:$399.99
Your Savings:$100.00(25%)
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Details

The Davidson Defense Marathon 14.5" Carbine-Gas 5.56 NATO AR-15 Pistol Build Kit with Magpul BTR Brace is designed for optimal performance and compliance-ready configuration. It features a 14.5" government profile barrel made from 4150 CrMoV steel with a phosphate finish, a 1:7 twist rate, and a KAK Industry A2 Extended Flash Hider. When installed, the flash hider brings the barrel length to rifle standards, making the build pin-and-weld ready—though not yet permanently affixed.


The Black Diamond Series billet upper receiver is machined from 6061-T6 aluminum and anodized for durability, paired with a 12" lightweight M-LOK minimalist handguard for streamlined accessory mounting. The kit includes a nitride-finished 9310 steel bolt carrier group, mil-spec AR-15 M4 charging handle, heavy-duty 6-position buffer tube, standard carbine recoil spring, and a Magpul BTR Pistol Brace—providing a stable, complete foundation for your next high-performance AR-15 build.

Specifications

Barrel Length: 14.5-inch

Barrel Caliber: 5.56x45mm NATO

Barrel Gas System Length: Carbine

Barrel Twist Rate: 1:7

Barrel Thread Pitch: 1/2x28

Barrel Material: 4150 CrMoV

Barrel Finish: Phosphate

Barrel Profile: Government

Gas Block Size: 0.750

Muzzle Device: A2 Extended Flash Hider

Muzzle Device Thread Pitch: 1/2x28

Muzzle Device Finish: Phosphate

Upper Receiver: Black Diamond Series AR-15 Billet Upper Receiver

Upper Receiver Material: 6061-T6 Aluminum

Upper Receiver Finish: Anodized

Handguard: AR-15 Ultra-Lightweight Minimalist Handguard 12"

Handguard Length: 12-inch

Handguard Material: Aircraft-Grade Aluminum

Handguard Color: Black

Handguard Style: M-LOK

Charging Handle: AR-15 M4 Charging Handle Mil-Spec Quality

Bolt Carrier: AR-15 5.56/.223/.300/.350 Complete Bolt Carrier Group

Bolt Carrier Material: 9310 Alloy Steel

Bolt Carrier Finish: Nitride

Pistol Brace Name: BTR Pistol Brace

Pistol Brace Color: Black

Buffer Tube Name: Mil-Spec Heavy-Duty AR-15 6-Position Buffer Tube

Buffer Weight: 3 oz

Recoil Spring: Standard AR-15 Carbine Recoil Spring

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