Rossi Neptune 10.5″ SAS Black – HPA MechLabs XX-Mod Edition
£629.99
The Rossi Neptune 10.5″ SAS – HPA MechLabs XX-Mod Edition combines a full metal UKSF-style rifle with the factory-installed MechLabs XX-Mod mechanical HPA engine. Rossi Neptune SAS → mechanical HPA system → instant trigger response and exceptional shot consistency, therefore no batteries or FCUs are required.
Adjustable magnetic trigger → customised trigger feel → optimised performance for speedsoft and milsim use. Since the rifle retains V2 AEG magazine compatibility and rotary hop-up compatibility, it offers reliable operation, straightforward upgrades and excellent air efficiency.
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Description
The Rossi Neptune 10.5″ SAS – HPA MechLabs XX-Mod Edition delivers the performance advantages of HPA technology without the complexity of aftermarket conversions. Rossi → Neptune SAS HPA Rifle → factory-installed MechLabs XX-Mod engine, therefore users receive a professionally integrated system designed for reliability, consistency and rapid trigger response straight out of the box.
Built around the proven Neptune SAS chassis, this HPA airsoft rifle combines a robust full metal construction with a UKSF-inspired appearance. Since the rifle features a monolithic-style upper receiver and durable tan finish, it provides both realistic handling and modern tactical styling.
MechLabs XX-Mod Mechanical HPA Engine
At the core of this rifle sits the CNC-machined MechLabs XX-Mod engine. Unlike electro-pneumatic HPA systems, this mechanical unit operates without batteries, wiring or electronic control units, consequently reducing potential failure points whilst maintaining exceptional performance.
The pneumatic valve system produces an immediate trigger break and highly consistent air delivery. As a result, shot-to-shot FPS variation remains extremely low, helping improve accuracy and predictability during competitive gameplay and precision shooting.
- MechLabs XX-Mod Engine: Factory-installed CNC aluminium mechanical HPA engine.
- No Electronics Required: Operates entirely through pneumatic mechanics without batteries or FCUs.
- Adjustable Magnetic Trigger: Fine-tune trigger weight and travel to suit different play styles.
- Semi & Full Auto Modes: Supports versatile engagement options on the field.
- Full Metal Construction: Durable Neptune SAS receiver with premium tan finish.
- V2 Magazine Compatibility: Accepts standard V2 AEG magazines for easy integration.
- Rotary Hop-Up Compatibility: Compatible with standard rotary hop-up units and aftermarket upgrades.
- Tool-Less Maintenance: Simplifies servicing and routine maintenance.
- Integrated Safety Features: Includes a physical cut-off switch and built-in degassing system.
- Excellent Air Efficiency: Delivers up to approximately 800 shots from a standard 13ci / 3000 PSI tank.
Tunable Trigger Performance
Magnetic trigger system → adjustable travel and pull weight → customised shooting characteristics. Consequently, users can configure an ultra-short trigger pull for speedsoft or a heavier trigger break for realistic training and milsim loadouts.
The MechLabs XX-Mod also delivers impressive efficiency. Since the engine optimises air usage throughout the firing cycle, players can achieve extended shot counts whilst maintaining reliable performance throughout the day.
Available from Defcon Airsoft, the UK’s leading airsoft online store, the Rossi Neptune 10.5″ SAS – HPA MechLabs XX-Mod Edition offers mechanical HPA reliability, outstanding consistency and a premium UKSF-inspired rifle configuration for demanding airsoft players.
Please Note: An HPA tank, regulator and airline are required for operation and are sold separately.






