CNC NBU Nozzle

RetroArms CNC NBU Nozzle for New Bore Up Air Systems
Unlike a standard nozzle, its design is adapted to the NBU cylinder head and uses a twice-enlarged O-ring to provide a proper seal on the cylinder head. Despite the larger seal, the nozzle is designed to move freely and smoothly along the cylinder head. The body is precision CNC-turned from EN AW 2007 free-machining aluminium alloy, and the sealing O-ring is factory-installed inside the nozzle. RetroArms offers NBU nozzles in several lengths ranging from 19.6 to 22.5 mm and from 24.5 to 26 mm, allowing the correct length to be selected for a specific combination of gearbox, hop-up chamber and hop-up bucking. Correct nozzle length is essential for both BB feeding and air seal, so it should not be selected solely according to the gun platform. The O-ring must be lubricated before use to ensure smooth nozzle movement along the cylinder head without unnecessary resistance or excessive seal wear.
Key Features

Designed for NBU Air Systems
The nozzle is specifically designed for NBU (New Bore Up) cylinder heads used in air systems with increased air volume.

Enlarged Sealing O-Ring
Compared with the original design, the nozzle uses a twice-enlarged O-ring to provide a proper seal on the corresponding NBU cylinder head.

CNC-Turned EN AW 2007 Aluminium Alloy
The nozzle body is precision CNC-turned from EN AW 2007 free-machining aluminium alloy, allowing accurate machining of this air system component.

Multiple Lengths for Proper Build Matching
The available variants cover lengths of 19.6–22.5 mm and 24.5–26 mm, allowing the nozzle to be selected for the specific gun configuration.

Factory-Installed O-Ring
The sealing O-ring is factory-installed inside the nozzle. It only needs ..