Diamond Duck 9MM Upper Build

Diamond Duck 9MM Upper Build

This AR-9 upper combines a 4.5-inch nitride barrel with a billet aluminum receiver and free-float handguard for a compact, accurate platform. The KAK Industry compensator manages recoil while keeping the overall profile tight. Everything you need is included except the bolt carrier group and lower receiver.

Key Features

• 4.5-inch 4150 CrMoV nitride barrel with 1:10 twist rate
• 6061-T6 billet aluminum upper receiver, Type III hard coat anodized
• 4-inch M-LOK free-float handguard for accessory mounting
• KAK Industry 9mm mini compensator, 1/2x36 thread
• AR-15 M4 mil-spec charging handle included
• Crush washer included

Compact 9MM Platform

This build delivers a practical 9mm upper in a short package. The 4.5-inch barrel keeps overall length manageable while the nitride finish provides durability. The billet receiver and free-float handguard work together to maintain consistent accuracy across a range of shooting scenarios. The M-LOK slots give you plenty of options for lights, grips, and other accessories.

Recoil Management

The KAK Industry mini compensator is sized specifically for 9mm, reducing muzzle rise without adding excessive length or blast. The 1/2x36 thread pitch is standard for 9mm platforms. The compensator threads directly onto the barrel, and the included crush washer ensures proper alignment.

Handguard and Accessory Compatibility

The 4-inch free-float handguard isolates the barrel from the upper receiver, which helps maintain zero when you add or remove accessories. M-LOK slots run along the handguard for mounting rail sections, grips, and other gear. The handguard is aluminum like the receiver, keeping weight down while maintaining rigidity.

Follow safe handling and manufacturer instructions. Ensure compliance with all applicable federal, state, and local laws. BCG and charging handle are not included. Verify barrel thread pitch compatibility with any muzzle device you plan to use.