Davidson Defense Reentry 4.5-inch 1:10 9MM AR-9 Freefloat M-Lok Handguard Pistol Upper Build Kit

Reentry 4.5-inch 1:10 9mm AR-9 M-Lok Pistol Upper Build Kit

The Reentry 4.5-inch 1:10 9mm AR-9 M-Lok Pistol Upper Build Kit from Davidson Defense is an upper build kit for the AR-9 platform chambered in 9mm. The kit includes a 4.5-inch medium-profile barrel, a 4-inch black aluminum M-Lok handguard with full top rail, a 7075-T6 anodized upper receiver, and an A2 birdcage flash hider. BCG and charging handle are not included.

Key Features

• 4.5-inch 4150 CrMoV medium-profile barrel in 9mm with 1:10 twist rate
• Nitride barrel finish
• 1/2x36 muzzle thread pitch
• A2 birdcage flash hider, 1/2x36 TPI, manganese phosphate finish
• 4-inch black aluminum M-Lok handguard with full top rail
• 7075-T6 anodized aluminum upper receiver
• BCG and charging handle not included

Perfect For

• Builders completing a compact 9mm AR-9 pistol upper
• Shooters sourcing their own bolt carrier group and charging handle
• Builders prioritizing a short M-Lok handguard with full top rail on the AR-9 platform
• Those working within a blowback 9mm pistol upper configuration

Barrel and Handguard

The 4.5-inch barrel is chambered in 9mm and constructed from 4150 CrMoV steel with a medium profile and a 1:10 twist rate. The nitride finish covers the full barrel surface for corrosion and wear resistance. The muzzle is threaded 1/2x36 and includes an A2 birdcage flash hider with a manganese phosphate finish. The 4-inch black aluminum M-Lok handguard features a full top Picatinny rail and provides M-Lok slot access along its length for accessory mounting. The AR-9 platform operates on blowback, with no gas system components in this configuration.

Upper Receiver

The upper receiver is machined from 7075-T6 aluminum with an anodized finish. It is sized for the AR-9 platform and accepts the 9mm barrel profile included in this kit.

Follow safe handling and manufacturer instructions. Ensure compliance with all applicable federal, state, and local laws. BCG and charging handle are not included.