MechLabs XX-Mod Fully Mechanical HPA Engine for V2 Gearbox

The XX-Mod is the next generation of MechLabs' mechanical HPA platform, evolving the NEXXUS design that the brand built its reputation on. The headline change is in how it handles air: a newly engineered XX-Mold bolt assembly with an adjustable nozzle synchronises the internal air-cycle rate to the configured nozzle length. The result is reduced air consumption per shot, better burst stability with low-flow regulators, and noticeably tighter shot-to-shot grouping. It's also cross-compatible with existing NEXXUS and ARC owners who want the bolt upgrade alone.

What makes a fully mechanical engine appealing isn't speed — the XX-Mod isn't trying to compete with solenoid engines on raw ROF. It's about everything that goes wrong with electronics. No FCU to fail, no solenoid coils to burn out, no wiring loom to short, no firmware to update, no battery voltage to monitor. The trigger pull mechanically cycles the bolt and fires the BB. The engine is 100% waterproof and will operate fully submerged — relevant for UK winter games and outdoor sites that get genuinely wet.

Construction is CNC-milled Aluminium Series 6 throughout the engine block, with a precision lock-fit interface between modular sections so the engine can be partially disassembled for servicing without losing alignment. A 3-axis XYZ alignment system inside the block compensates for receiver tolerance differences, which means the engine fits cleanly into virtually any V2 shell — G&G, Specna Arms, Krytac, Tokyo Marui, VFC, ICS, KWA and similar. The trigger uses a magnetic return mechanism with adjustable travel and sensitivity for a crisp, repeatable feel.

Choose from nine anodised finishes. The Black and Grey options keep the visual profile of a stock gearbox; the coloured options (Blue, Green, Red, Purple, Pink, Teal, Gold) work well for skirmish builds where the engine is partially visible through a cut-out lower receiver or for tournament setups where finish matching is part of the build. Functionally identical across all nine colours — the anodising is cosmetic.

Specifications