Davidson Defense Marathon 14.5" 5.56 NATO AR-15 Pistol Build Kit, M-LOK Handguard, 1:7, w/ SBA3 Brace

Marathon 14.5" 5.56 NATO AR-15 Pistol Build Kit, M-LOK Handguard, 1:7, w/ SBA3 Brace

The Marathon 14.5-inch pistol build kit delivers a complete upper assembly paired with all the components needed to finish a lower receiver into a functional AR-15 pistol platform. This full build kit includes a carbine-length gas system, premium bolt carrier group, and an SB Tactical SBA3 adjustable stabilizing brace for customizable fit and control.

Key Features

• 14.5-inch 4150 CrMoV barrel with 1:7 twist rate for 5.56 NATO
• Carbine-length gas system with 0.750 gas block for reliable cycling
• Recoil Technologies premium bolt carrier group in 9310 alloy steel with nitride finish
• Aircraft-grade aluminum M-LOK handguard for accessory mounting flexibility
• SB Tactical SBA3 adjustable brace with multiple position settings
• Type III hard coat anodized upper receiver for durability
• Mil-spec M4 charging handle
• Pin and weld ready barrel configuration

Perfect For

• Builders looking for a complete pistol platform without the lower receiver
• Shooters wanting a compact 5.56 NATO configuration with adjustable brace support
• Those seeking a versatile build with modern ergonomics and modularity
• Pistol platform users prioritizing quality components and reliable performance

Marathon Pistol Build Philosophy

This kit combines proven AR-15 platform reliability with pistol-specific ergonomics. The 14.5-inch barrel length paired with carbine gas system tuning delivers consistent cycling across a wide range of ammunition while maintaining a compact overall footprint. The M-LOK handguard provides clean integration for tactical accessories without excess weight.

SBA3 Brace Configuration

The SB Tactical SBA3 brace ships with this kit and offers multiple adjustment positions to accommodate different grip preferences and shooting styles. The brace is designed to stabilize the pistol during firing while allowing customization based on your hand size and control needs. This configuration is intended for shooters selecting their own final setup based on personal preference and applicable regulations.

Component Quality and Materials

Premium materials define this build. The 4150 CrMoV barrel withstands repeated firing cycles while maintaining accuracy potential. The 9310 alloy steel bolt carrier with nitride finish resists wear and corrosion. Aircraft-grade aluminum in both the upper receiver and handguard keeps weight manageable without sacrificing structural integrity. Type III hard coat anodizing provides robust protection against daily use and environmental exposure.

Follow safe handling and manufacturer instructions. Ensure compliance with all applicable federal, state, and local laws. Lower receiver not included. Do not attach a stock unless compliant with applicable laws.