DURAL 2013 NBU Piston Head

AirsoftParts DURAL 2013 NBU Piston Head for Bore Up Air Seal Systems
Compared with the standard piston head, the NBU version has larger dimensions to match the Bore Up system with increased air volume and can therefore be combined only with an NBU cylinder. The front features 9 holes through which air flows beneath the main sealing O-ring during compression. The pressure expands it against the cylinder wall and promotes effective sealing. A second guide O-ring helps center the metal piston head inside the cylinder and reduces the risk of unwanted contact with the cylinder wall. The rear section is lightened, resulting in a total weight of 11.4 g. The design also incorporates an axial ball bearing that allows the spring to rotate more freely during compression. The manufacturer recommends use with springs up to M170 and states compatibility with V2, V3 and V7 gearboxes when used with the corresponding NBU air seal system. Made in the Czech Republic.
Key Features

NBU Design for Bore Up Systems
The enlarged dimensions of the piston head correspond to NBU / Bore Up air seal systems with increased air volume. The piston head must be combined with the corresponding NBU cylinder.

Guide O-Ring for Proper Centering
In addition to the main seal, the design uses a separate guide O-ring that helps keep the duralumin piston head centered and reduces contact with the inner cylinder wall.

9 Holes for Pressure-Assisted Sealing
The 9 front holes direct air beneath the sealing O-ring during compression. The pressure expands it against the NBU cylinder wall and helps effectively seal the piston assembly.

Durable Duralumin and Lightweight Design
The piston head is CNC-machined from EN AW 6012 T6 dural..