Rossi Neptune 10.5″ SAS BK - HPA Edition (MechLabs XX-Mod)

The Rossi Neptune 10.5″ SAS BK - HPA Edition pairs the highly revered British SAS L119A2 external architecture with the relentless reliability of a 100% mechanical pneumatic engine. Purpose-built to perform in the harshest global climates, this high-end platform hands you the extreme consistency of custom HPA builds without any technical headaches or electrical components.

The MechLabs XX-Mod Mechanical Engine The beating heart of this rifle is the premium, CNC-milled Series 6 Aluminium MechLabs XX-Mod Engine. Unlike standard electro-pneumatic setups that depend on fragile LiPo batteries and mosfets, the XX-Mod runs purely on air pressure. This grants a massive tactical advantage on the field: the entire engine is completely waterproof. You can confidently push through torrential rain or sub-zero winter temperatures without ever worrying about short-circuits. Because there is no electronic signal transition time, the advanced pneumatic valve system delivers absolute zero trigger delay—snapping shots off instantly the moment the trigger breaks.

Optimized Efficiency & Magnetic Trigger To maximize your field endurance, the internal core leverages an optimized XX-Mold Bolt System. This design slashes air consumption per shot, extracting substantially more rounds out of a standard HPA tank while stabilizing output pressure during rapid full-auto strings to eradicate muzzle velocity drop-off. For unmatched shooter personalization, the rifle features an adjustable Magnetic Return Trigger. Without tearing down the gearbox, users can quickly fine-tune both travel distance and pull weight to lock in an ultra-crisp "hair trigger" for lightning-fast semi-auto cycling.

Elite UKSF Aesthetics & Pre-Upgraded Precision Externally, the Neptune SAS is finished in sleek matte black and beautifully mirrors the definitive L119A2 combat rifle. It features a rock-solid, full-metal monolithic upper receiver coupled with an integrated quad-rail handguard that offers immense real estate for scopes, tactical flashlights, and PEQ laser boxes. Down the business end, Rossi has twinned this pneumatic force with an elite barrel group: a 6.02mm precision tightbore inner barrel paired with a genuine Maple Leaf Super Macaron Hop-Up Bucking and an Omega Nub for flat, predictable tracking over extreme distances.

Key Technical Features:

• Factory Installed HPA Setup: Pre-fitted with the premium, CNC-milled MechLabs XX-Mod mechanical engine.

• 100% Mechanical Operation: Requires zero batteries or electronics; fully waterproof and immune to bad weather.

• Adjustable Magnetic Trigger: Fine-tune trigger weight and take-up distance on the fly for customized response.

• XX-Mold Bolt Efficiency: Minimizes air consumption while optimizing burst stability.

• Authentic UKSF Styling: Full-metal construction featuring a monolithic receiver layout and quad-rail front end.

• Maple Leaf Barrel Group: Includes a 6.02mm tightbore barrel, Super Macaron bucking, and Omega nub.

Field & Maintenance Recommendations The Rossi Neptune SAS HPA operates across a site-safe 301–350 FPS bracket, depending on your external regulator settings. It is fully compatible with standard V2 M4 AEG magazines and rotary hop-up upgrades. To stay in peak shape, ensure your HPA line is clean before connecting. A light coating of premium synthetic tech grease on the main bolt seals every few months keeps the mechanical cycle running flawlessly. (Note: Requires an external HPA tank, remote line, and regulator to operate, sold separately).